版权声明:尚开源精神,亦需版权意识 https://blog.csdn.net/u013427969/article/details/81000654
#include <ctime>
#include <iostream>
#include <cmath>
using namespace std;
const int N = 1024;
int main(void)
{
int i, M;
time_t t1 = time(NULL);
for(int r = 0; r < 100000000; r++)
for(i=N,M=1;(i=i/2)!=1;M++);
time_t t2 = time(NULL);
for(int r = 0; r < 100000000; r++)
M = log(N)/log(2);
time_t t3 = time(NULL);
cout << "time1:" << t2 - t1 << "\ntime2:" << t3 - t2 << endl;
return 0;
}
/*
* res:
* time1:4
* time2:13
*/