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----------

Purpose:

First, sorry for my bad English.
Second, I know there are lots of topics about this. But after solving a problem that need FastIO, I feel interested in FastIO and decide to do the implementations and comparing them. But it maybe time-consuming so I make this post for ones who maybe try to find the Effeciency-Simple-IO, so you can save time instead of searching more.
Third, usually it is need not to use FastIO. In the contest, they usually have twice or more time of the solutions code than the given time limitation. Dont worry about faster IO if it is not needed, you should improve your algorithms first, maybe you can use Bitwise Operations for x8 x32 x64 faster.
Fourth, if the problem need to be solve in O(n) ~ O(n log n), and your algorithms work in O(n ^ 2), this Micro-Optimization doesnt help you at all (maybe you will get some more points but hard get AC), you should change the algorithms for further approach.
Final, for some problems that needed to be solved by FastIO, you can use the suitable template and modify it for your solving the problem. Dont use the template if you dont really know how to use (I may add a guide path to the post in the future)
Conclusion, this post is about comparing the implementations for each version of C++ language and you should choose the most suitable for you.

Here are some implementations to output numbers I found

Time to write first 10.000.000 non-negative numbers

(base on Codeforces Custom Test // GNU G++ 17 7.3.0 // GNU G++ 14 6.4.0 // GNU G++ 11 5.1.0)

Sort by GNU G++ 17 7.3.0

Putchar Non-recursive Dividing Implementation: 3649ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        putchar(x / p + '0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Recursive Implementation: 3510ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Reverse Implementation: 3462ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Non-recursive toString Implementation: 3369ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Printf Implementation: 1762ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) printf("%d", q);
    return 0;
}

synchronized(off) Cout Implementation: 1356ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

synchronized(true) Cout Implementation: 1060ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

Normal Cout Implementation: 1045ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

Unlocked-Putchar Non-recursive Dividing Implementation: 919ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) _putchar_nolock('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        _putchar_nolock(x / p + '0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Unlocked-Putchar Reverse Implementation: 842ms

#include <iostream>

using namespace std;

#define pc _putchar_nolock
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Unlocked-Putchar Recursive Implementation: 701ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    _putchar_nolock(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) _putchar_nolock('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Unlocked-Putchar Non-recursive toString Implementation: 670ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) _putchar_nolock('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) _putchar_nolock(os[i] + 48);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

fwrite buffer Implementation: 545ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;

int main()
{
    int q = 1e7;
    while (q--) writeInt(q); Flusher();
    return 0;
}

Sort by GNU G++ 14 6.4.0

Putchar Non-recursive Dividing Implementation: 3525ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        putchar(x / p + '0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Reverse Implementation: 3447ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Recursive Implementation: 3354ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Non-recursive toString Implementation: 3353ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Printf Implementation: 1669ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) printf("%d", q);
    return 0;
}

synchronized(off) Cout Implementation: 1356ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

synchronized(true) Cout Implementation: 1091ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

Normal Cout Implementation: 1075ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

Unlocked-Putchar Non-recursive Dividing Implementation: 888ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) _putchar_nolock('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        _putchar_nolock(x / p + '0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Unlocked-Putchar Reverse Implementation: 685ms

#include <iostream>

using namespace std;

#define pc _putchar_nolock
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Unlocked-Putchar Recursive Implementation: 561ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    _putchar_nolock(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) _putchar_nolock('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Unlocked-Putchar Non-recursive toString Implementation: 546ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) _putchar_nolock('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) _putchar_nolock(os[i] + 48);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

fwrite buffer Implementation: 498ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;

int main()
{
    int q = 1e7;
    while (q--) writeInt(q); Flusher();
    return 0;
}

Sort by GNU G++ 11 5.1.0

synchronized(off) Cout Implementation: 2901ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

synchronized(true) Cout Implementation: 2901ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

Normal Cout Implementation: 2900ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

Printf Implementation: 1918ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) printf("%d", q);
    return 0;
}

Putchar Non-recursive Dividing Implementation: 795ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        putchar(x / p + '0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Reverse Implementation: 592ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Non-recursive toString Implementation: 451ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Recursive Implementation: 389ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

fwrite buffer Implementation: 405ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;

int main()
{
    int q = 1e7;
    while (q--) writeInt(q); Flusher();
    return 0;
}

Sort by Microsoft Visual C++ 2010

synchronized(true) Cout Implementation: 4477ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

synchronized(off) Cout Implementation: 4414ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

Normal Cout Implementation: 4351ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

Putchar Reverse Implementation: 2667ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Non-recursive Dividing Implementation: 2666ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        putchar(x / p + '0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Non-recursive toString Implementation: 2635ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Recursive Implementation: 2620ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Printf Implementation: 2058ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) printf("%d", q);
    return 0;
}

fwrite buffer Implementation: 358ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;

int main()
{
    int q = 1e7;
    while (q--) writeInt(q); Flusher();
    return 0;
}

Sort by Microsoft Visual C++ 2017

synchronized(off) Cout Implementation: 5241ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

synchronized(true) Cout Implementation: 5210ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

Normal Cout Implementation: 5054ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) cout << q;
    return 0;
}

Putchar Non-recursive Dividing Implementation: 2558ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        putchar(x / p + '0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Reverse Implementation: 2557ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Non-recursive toString Implementation: 2542ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Putchar Recursive Implementation: 2527ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(q);
    return 0;
}

Printf Implementation: 2230ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) printf("%d", q);
    return 0;
}

fwrite buffer Implementation: 311ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;

int main()
{
    int q = 1e7;
    while (q--) writeInt(q); Flusher();
    return 0;
}

Time to write 1.000 times first 10000 numbers

(base on Codeforces Custom Test // GNU G++ 17 7.3.0 // GNU G++ 14 6.4.0 // GNU G++ 11 5.1.0)

Sort by GNU G++ 17 7.3.0

Putchar Reverse Implementation: 1981ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Putchar Non-recursive Dividing Implementation: 1980ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        putchar(x / p + '0');
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Putchar Non-recursive toString Implementation: 1934ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Putchar Recursive Implementation: 1887ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Printf Implementation: 1216ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            printf("%d", i);
    return 0;
}

synchronized(on) Implementation: 873ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

Normal Cout Implementation: 873ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

synchronized(off) Cout Implementation: 857ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

Unlocked-Putchar Non-recursive Dividing Implementation: 483ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) _putchar_nolock('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        _putchar_nolock(x / p + '0');
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Unlocked-Putchar Reverse Implementation: 467ms

#include <iostream>

using namespace std;

#define pc _putchar_nolock
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Unlocked-Putchar Recursive Implementation: 358ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    _putchar_nolock(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) _putchar_nolock('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Unlocked-Putchar Non-recursive toString Implementation: 373ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) _putchar_nolock('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) _putchar_nolock(os[i] + 48);
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

fwrite buffer Implementation: 311ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;


int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    Flusher();
    return 0;
}

Sort by GNU G++ 14 6.4.0

Putchar Reverse Implementation: 1996ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Putchar Non-recursive Dividing Implementation: 1996ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        putchar(x / p + '0');
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Putchar Non-recursive toString Implementation: 1903ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Putchar Recursive Implementation: 1871ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Printf Implementation: 1153ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            printf("%d", i);
    return 0;
}

synchronized(off) Cout Implementation: 920ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

synchronized(on) Implementation: 888ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

Normal Cout Implementation: 873ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

Unlocked-Putchar Non-recursive Dividing Implementation: 452ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) _putchar_nolock('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        _putchar_nolock(x / p + '0');
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Unlocked-Putchar Reverse Implementation: 404ms

#include <iostream>

using namespace std;

#define pc _putchar_nolock
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Unlocked-Putchar Non-recursive toString Implementation: 296ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) _putchar_nolock('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) _putchar_nolock(os[i] + 48);
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Unlocked-Putchar Recursive Implementation: 295ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    _putchar_nolock(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) _putchar_nolock('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

fwrite buffer Implementation: 233ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;


int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    Flusher();
    return 0;
}

Sort by GNU G++ 11 5.1.0

synchronized(on) Implementation: 2698ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

Normal Cout Implementation: 2698ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

synchronized(off) Cout Implementation: 2620ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

Printf Implementation: 1403ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            printf("%d", i);
    return 0;
}

Putchar Non-recursive Dividing Implementation: 405ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        putchar(x / p + '0');
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Putchar Reverse Implementation: 343ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

fwrite buffer Implementation: 265ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;


int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    Flusher();
    return 0;
}

Putchar Non-recursive toString Implementation: 249ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Putchar Recursive Implementation: 233ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Sort by Microsoft Visual C++ 2010

Normal Cout Implementation: 3962ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

synchronized(on) Implementation: 3915ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

synchronized(off) Cout Implementation: 3884ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

Printf Implementation: 1715ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            printf("%d", i);
    return 0;
}

Putchar Reverse Implementation: 1559ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Putchar Non-recursive Dividing Implementation: 1544ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        putchar(x / p + '0');
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Putchar Recursive Implementation: 1513ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Putchar Non-recursive toString Implementation: 1512ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

fwrite buffer Implementation: 202ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;


int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    Flusher();
    return 0;
}

Sort by Microsoft Visual C++ 2017

synchronized(on) Implementation: 4772ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

synchronized(off) Cout Implementation: 4710ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

Normal Cout Implementation: 4695ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            cout << i;
    return 0;
}

Printf Implementation: 1747ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            printf("%d", i);
    return 0;
}

Putchar Non-recursive Dividing Implementation: 1435ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        putchar(x / p + '0');
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Putchar Reverse Implementation: 1435ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Putchar Non-recursive toString Implementation: 1419ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

Putchar Recursive Implementation: 1419ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    return 0;
}

fwrite buffer Implementation: 171ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;


int main()
{
    int q = 1e3;
    while (q--)
        for (int i = 0; i <= 1e4; ++i)
            writeInt(i);
    Flusher();
    return 0;
}

Time to write first 10.000.000 non-positive numbers

(base on Codeforces Custom Test // GNU G++ 17 7.3.0 // GNU G++ 14 6.4.0 // GNU G++ 11 5.1.0)

Sort by GNU G++ 17 7.3.0

Putchar Non-recursive toString Implementation: 3946ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Putchar Reverse Implementation: 3930ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Putchar Recursive Implementation: 3915ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-');
    writeRec(abs(x));
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Putchar Non-recursive Dividing Implementation: 3883ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10) putchar(x / p + '0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Printf Implementation: 1808ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) printf("%d", -q);
    return 0;
}

synchronized(off) Cout Implementation: 1481ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

synchronized(true) Cout Implementation: 1092ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

Normal Cout Implementation: 1092ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

Unlocked-Putchar Non-recursive Dividing Implementation: 1045ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) _putchar_nolock('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        _putchar_nolock(x / p + '0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Unlocked-Putchar Reverse Implementation: 857ms

#include <iostream>

using namespace std;

#define pc _putchar_nolock
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Unlocked-Putchar Non-recursive toString Implementation: 795ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) _putchar_nolock('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) _putchar_nolock(os[i] + 48);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Unlocked-Putchar Recursive Implementation: 779ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    _putchar_nolock(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) _putchar_nolock('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

fwrite buffer Implementation: 561ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q); Flusher();
    return 0;
}

Sort by GNU G++ 14 6.4.0

Putchar Reverse Implementation: 3899ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Putchar Recursive Implementation: 3899ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-');
    writeRec(abs(x));
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Putchar Non-recursive Dividing Implementation: 3883ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10) putchar(x / p + '0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Putchar Non-recursive toString Implementation: 3860ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Printf Implementation: 1762ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) printf("%d", -q);
    return 0;
}

synchronized(off) Cout Implementation: 1512ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

Normal Cout Implementation: 1153ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

synchronized(true) Cout Implementation: 1092ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

Unlocked-Putchar Non-recursive Dividing Implementation: 951ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) _putchar_nolock('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10)
        _putchar_nolock(x / p + '0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Unlocked-Putchar Reverse Implementation: 732ms

#include <iostream>

using namespace std;

#define pc _putchar_nolock
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Unlocked-Putchar Recursive Implementation: 655ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    _putchar_nolock(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) _putchar_nolock('-'), x = -x;
    writeRec(x);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Unlocked-Putchar Non-recursive toString Implementation: 638ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) _putchar_nolock('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) _putchar_nolock(os[i] + 48);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

fwrite buffer Implementation: 529ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q); Flusher();
    return 0;
}

Sort by GNU G++ 11 5.1.0

synchronized(true) Cout Implementation: 2901ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

Normal Cout Implementation: 2901ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

synchronized(off) Cout Implementation: 2885ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

Printf Implementation: 1950ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) printf("%d", -q);
    return 0;
}

Putchar Non-recursive Dividing Implementation: 810ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10) putchar(x / p + '0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Putchar Reverse Implementation: 624ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

fwrite buffer Implementation: 483ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q); Flusher();
    return 0;
}

Putchar Non-recursive toString Implementation: 483ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Putchar Recursive Implementation: 452ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-');
    writeRec(abs(x));
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Sort by Microsoft Visual C++ 2010

synchronized(true) Cout Implementation: 4508ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

Normal Cout Implementation: 4461ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

synchronized(off) Cout Implementation: 4461ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

Putchar Reverse Implementation: 3057ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Putchar Recursive Implementation: 3025ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-');
    writeRec(abs(x));
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Putchar Non-recursive toString Implementation: 2995ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Putchar Non-recursive Dividing Implementation: 2994ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10) putchar(x / p + '0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Printf Implementation: 2090ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) printf("%d", -q);
    return 0;
}

fwrite buffer Implementation: 374ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q); Flusher();
    return 0;
}

Sort by Microsoft Visual C++ 2017

synchronized(true) Cout Implementation: 5225ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

synchronized(off) Cout Implementation: 5163ms

#include <iostream>

using namespace std;

int main()
{
    ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

Normal Cout Implementation: 5148ms

#include <iostream>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) cout << -q;
    return 0;
}

Putchar Reverse Implementation: 2932ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-'), n = -n;
    if (!n) return (void)pc('0');
    int t = n, cnt = 0, rev = 0;
    while (!(t%10)) { cnt++; t /= 10;}
    do {rev=rev*10 + n%10;} while(n /= 10);
    do {pc(rev % 10 + 48);} while(rev /= 10);
    while (cnt--) pc('0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Putchar Non-recursive Dividing Implementation: 2885ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    if (x < 0) putchar('-'), x = -x;
    int p = 1;
    for (int t = x / 10; t > 0; t /= 10)
        p *= 10;
    for (; p > 0; x %= p, p /= 10) putchar(x / p + '0');
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Putchar Recursive Implementation: 2870ms

#include <iostream>

using namespace std;

inline void writeRec(int n) {
    if (n > 9) writeRec(n / 10);
    putchar(char(n % 10 + '0'));
}

inline void writeInt(int x)
{
    if (x < 0) putchar('-');
    writeRec(abs(x));
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Putchar Non-recursive toString Implementation: 2807ms

#include <iostream>

using namespace std;

char os[20];
inline void writeInt(int n)
{
    if (n < 0) putchar('-'), n = -n;
    int i=0;
    do os[i++] = n%10; while(n/=10);
    while (i--) putchar(os[i] + 48);
}

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q);
    return 0;
}

Printf Implementation: 2245ms

#include <cstdio>

using namespace std;

int main()
{
    int q = 1e7;
    while (q--) printf("%d", -q);
    return 0;
}

fwrite buffer Implementation: 342ms

#include <iostream>

using namespace std;

static const int buf_len = (1 << 14);
static const int buf_max = (1 << 04);
static char buf_out[buf_len];
static char buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x) {
    if (buf_pos == buf_len) fwrite(buf_out, 1, buf_len, stdout), buf_pos = 0;
    buf_out[buf_pos++] = x;
}

inline void writeInt(int x, char end = 0) {
    if (x < 0) writeChar('-'), x = -x;
    int n = 0;
    do buf_num[n++] = x % 10 + '0'; while(x /= 10);
    while (n--) writeChar(buf_num[n]);
    if (end) writeChar(end);
}

struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;

int main()
{
    int q = 1e7;
    while (q--) writeInt(-q); Flusher();
    return 0;
}

Single Line Template

Putchar Non-recursive toString Implementation

char os[20];
inline void writeInt(int n){if(n<0)putchar('-'),n=-n;int i=0;do{os[i++]=n%10;}while(n/=10);while(i--)putchar(os[i]+48);}

Putchar Non-recursive Dividing Implementation

inline void writeInt(int x){if(x<0)putchar('-'),x=-x;int p=1;for(int t=x/10;t>0;t/=10)p*=10;for(;p>0;x%=p,p/=10)putchar(x/p+'0');}

Putchar Reverse Implementation

#define pc putchar
inline void writeInt(int n){if(n<0)pc('-'),n=-n;if(!n)return(void)pc('0');int t=n,cnt=0,rev=0;while(!(t%10)){cnt++;t/=10;}do{rev=rev*10+n%10;}while(n/=10);do{pc(rev%10+48);}while(rev/=10);while(cnt--)pc('0');}

Putchar Recursive Implementation

inline void writeRec(int n){if(n>9)writeRec(n/10);putchar(char(n%10+'0'));}
inline void writeInt(int x){if(x<0)putchar('-');writeRec(abs(x));}

Unlocked-Putchar Non-recursive toString Implementation

char os[20];
inline void writeInt(int n){if(n<0)_putchar_nolock('-'),n=-n;int i=0;do{os[i++]=n%10;}while(n/=10);while(i--)_putchar_nolock(os[i]+48);}

Unlocked-Putchar Non-recursive Dividing Implementation

inline void writeInt(int x){if(x<0)_putchar_nolock('-'),x=-x;int p=1;for(int t=x/10;t>0;t/=10)p*=10;for(;p>0;x%=p,p/=10)_putchar_nolock(x/p+'0');}

Unlocked-Putchar Reverse Implementation

#define pc _putchar_nolock
inline void writeInt(int n){if(n<0)pc('-'),n=-n;if(!n)return(void)pc('0');int t=n,cnt=0,rev=0;while(!(t%10)){cnt++;t/=10;}do{rev=rev*10+n%10;}while(n/=10);do{pc(rev%10+48);}while(rev/=10);while(cnt--)pc('0');}

Unlocked-Putchar Recursive Implementation

inline void writeRec(int n){if(n>9)writeRec(n/10);_putchar_nolock(char(n%10+'0'));}
inline void writeInt(int x){if(x<0)_putchar_nolock('-');writeRec(abs(x));}

Printf Implementation

printf("%d", x);

synchronized(off) Implementation

ios::sync_with_stdio(NULL),cin.tie(NULL),cout.tie(NULL);

synchronized(true) Implementation

ios::sync_with_stdio(true),cin.tie(NULL),cout.tie(NULL);

Cout Implementation

cout << x;

fwrite buffer Implementation

static const int buf_len = (1 << 14), buf_max = (1 << 04);
static char buf_out[buf_len], buf_num[buf_max];
static int buf_pos = 0;

inline void writeChar(int x){if(buf_pos==buf_len)fwrite(buf_out,1,buf_len,stdout),buf_pos=0;buf_out[buf_pos++]=x;}
inline void writeInt(int x,char end=0){if(x<0)writeChar('-'),x=-x;int n=0;do{buf_num[n++]=x%10+'0';}while(x/=10);while(n--)writeChar(buf_num[n]);if(end)writeChar(end);}
struct Flusher{~Flusher(){if(buf_pos)fwrite(buf_out, 1, buf_pos, stdout),buf_pos=0;}}flusher;

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Planning:

Test about random 10.000.000 big numbers
Test about 10.000.000 numbers 2 ^ k, k integer
More implementations (Actually the post is about Faster and Faster Short Output Implementation but I will add some for speed comparing)
New output types (long long, double, string)

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SPyofgame's blog

Purpose:

Here are some implementations to output numbers I found

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