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

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Here are some implementation to output numbers I found and the time to write [first 10.000.000 numbers] (base on Codeforces Custom Test // GNU G++ 17 7.3.0)

Putchar Recursive Implementation: 3525ms

#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 Implementation: 3525ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    int p = 1;
    for (int temp = x / 10; temp > 0; temp /= 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: 3493ms

#include <iostream>

using namespace std;

#define pc putchar
inline void writeInt(int n)
{
    if (n < 0) pc('-');
    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;
}

Printf Implementation: 1762ms

#include <cstdio>

using namespace std;

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

synchronized(off) 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) 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 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;
}

Here are some implementation to output numbers I found and the time to write [1.000 times first 10000 numbers] (base on Codeforces Custom Test // 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('-');
    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 Implementation: 1980ms

#include <iostream>

using namespace std;

inline void writeInt(int x)
{
    int p = 1;
    for (int temp = x / 10; temp > 0; temp /= 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: 1808ms

#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 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) 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;
}

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)

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