C++ Output Implementations // Are there ways to perform faster ?

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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;
}

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;
}

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;
}

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;
}

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;
}

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;
}

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;
}

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;
}

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 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;
}

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 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;
}

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;
}

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 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));}

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');}

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;

---------- About: ----------

---------- Planning: ----------

Test about random 10.000.000 big numbers
Test with GNU G++ 14 6.4.0
Test with GNU G++ 11 5.1.0
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)

Rev.	By	When	Δ	Comment
en44	SPyofgame	2020-06-06 17:24:10	2	Tiny change: '\n\n\n\n\n' -> '\n\n\n\n\n\n'
en43	SPyofgame	2020-06-01 04:54:23	24664	Add Sort by Microsoft Visual C++ 2010 \| Add Sort by Microsoft Visual C++ 2017
en42	SPyofgame	2020-03-11 17:17:22	246
en41	SPyofgame	2020-03-11 17:16:30	585
en40	SPyofgame	2020-03-11 17:07:19	1028
en39	SPyofgame	2020-03-11 16:19:02	5	Tiny change: '\n- _[C++ Output Implem' -> '\n- _[C++ Input Implem'
en38	SPyofgame	2020-03-11 16:17:54	828
en37	SPyofgame	2020-03-11 16:00:33	163
en36	SPyofgame	2020-03-11 15:32:22	3
en35	SPyofgame	2020-03-11 13:43:24	46	Tiny change: '-- \n\n- _Test ' -> '-- \n\n- _Start working on `Input Implementation`_\n- _Test '
en34	SPyofgame	2020-03-11 12:13:31	13359
en33	SPyofgame	2020-03-10 17:02:27	66
en32	SPyofgame	2020-03-10 16:57:31	2020
en31	SPyofgame	2020-03-10 16:45:15	17395
en30	SPyofgame	2020-03-10 15:13:24	436
en29	SPyofgame	2020-03-10 15:04:53	11184
en28	SPyofgame	2020-03-09 17:08:42	23	Tiny change: '_\n- _New type of implementations (long lo' -> '_\n- _New output types (long lo'
en27	SPyofgame	2020-03-09 17:08:00	107
en26	SPyofgame	2020-03-09 17:04:42	56
en25	SPyofgame	2020-03-09 17:02:11	259	Tiny change: ' 14 6.4.0`_\n- _Test' -> ' 14 6.4.0` for who_\n- _Test'
en24	SPyofgame	2020-03-08 14:31:46	1	Tiny change: 'ementation to output' -> 'ementations to output'
en23	SPyofgame	2020-03-08 13:35:10	56
en22	SPyofgame	2020-03-08 13:34:24	62
en21	SPyofgame	2020-03-08 13:32:27	151
en20	SPyofgame	2020-03-08 13:31:05	22
en19	SPyofgame	2020-03-08 13:30:04	643
en18	SPyofgame	2020-03-08 13:23:01	2	Tiny change: 't[buf_len]. buf_num[b' -> 't[buf_len], buf_num[b'
en17	SPyofgame	2020-03-08 13:21:59	2393
en16	SPyofgame	2020-03-08 06:24:35	1405
en15	SPyofgame	2020-03-08 05:43:13	2610
en14	SPyofgame	2020-03-07 21:43:54	1881
en13	SPyofgame	2020-03-07 21:05:24	16
en12	SPyofgame	2020-03-07 21:00:12	68
en11	SPyofgame	2020-03-07 17:34:09	40
en10	SPyofgame	2020-03-07 13:05:13	3986
en9	SPyofgame	2020-03-07 12:49:33	421
en8	SPyofgame	2020-03-07 12:34:04	128
en7	SPyofgame	2020-03-07 12:32:50	28
en6	SPyofgame	2020-03-07 12:32:25	200
en5	SPyofgame	2020-03-07 12:17:57	217
en4	SPyofgame	2020-03-07 12:16:16	502
en3	SPyofgame	2020-03-07 12:12:35	9
en2	SPyofgame	2020-03-07 12:11:11	16	Tiny change: ' summary="Third Implement' -> ' summary="synchronized(off) Implement'
en1	SPyofgame	2020-03-07 12:10:26	2318	Initial revision (published)

Here are some implementations to output numbers I found

History