pylimer-tools/fmt-vs-tostr.cpp at main · GenieTim/pylimer-tools · GitHub

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#include <random>

#include <algorithm>
#include <cassert>
#include <cstdlib>
#include <format>
#include <iostream>
#include <sstream>
#include <string>

typedef int64_t msec_t;
#if defined(__WIN32__)
#include <windows.h>
msec_t
currentTimeInMillis(void)
{
    return timeGetTime();
}
#else
#include <sys/time.h>
msec_t
currentTimeInMillis(void)
{
    struct timeval tv;
    gettimeofday(&tv, NULL);
    return (msec_t)tv.tv_sec * 1000 + tv.tv_usec / 1000;
}
#endif

int
main(int argc, char* argv[])
{
    msec_t start;
    msec_t stop;

    long MAXCOUNT = 10000000;

    std::srand(123);

    int* numbers = new int[MAXCOUNT];
    for (int i = 0; i < MAXCOUNT; i++) {
        numbers[i] = std::rand();
    }

    {
        std::string result;
        result.reserve(MAXCOUNT * 100);
        start = currentTimeInMillis();
        for (int i = 0; i < MAXCOUNT; i++) {
            std::format_to(
                std::back_inserter(result), "Number {} is great!", numbers[i]);
        }
        stop = currentTimeInMillis();
        assert(result.size() > MAXCOUNT);
        std::cout << "timing fmt: " << stop - start
                  << " ms   /   string length: " << result.size() << std::endl;
    }

    {
        std::string result;
        result.reserve(MAXCOUNT * 100);
        start = currentTimeInMillis();
        for (int i = 0; i < MAXCOUNT; i++) {
            result += "Number " + std::to_string(numbers[i]) + " is great!";
        }
        stop = currentTimeInMillis();
        assert(result.size() > MAXCOUNT);
        std::cout << "timing to_string: " << stop - start
                  << " ms   /   string length: " << result.size() << std::endl;
    }

    {
        std::string result;
        result.reserve(MAXCOUNT * 100);
        std::ostringstream ss;
        start = currentTimeInMillis();
        for (int i = 0; i < MAXCOUNT; i++) {
            ss << "Number " << numbers[i] << " is great!";
        }
        result = ss.str();
        stop = currentTimeInMillis();
        assert(result.size() > MAXCOUNT);
        std::cout << "timing stds: " << stop - start
                  << " ms   /   string length: " << result.size() << std::endl;
    }
}