#include <iostream>
#include <string>
#include <cstring>
 
const int size = 100000000;
 
static char s_str[size];
 
int main()
{
    memset(s_str, 'x', size - 1);
 
    std::string s(s_str);
    clock_t c1, c2, c3, c4;
 
    // =
    c1 = clock();
    for (int i = 0; i < 10; i++) {
        s = s_str;
    }
    c2 = clock();
 
    // = std::string
    c3 = clock();
    for (int i = 0; i < 10; i++) {
        s = std::string(s_str);
    }
    c4 = clock();
 
    printf("=             : %d\n", static_cast<int>(c2 - c1));
    printf("= std::string : %d\n", static_cast<int>(c4 - c3));
}