可参考：https://www.linuxidc.com/Linux/2012-06/61903p2.htm
在计算多线程程序运行时间的时候，用可能会出问题，但是用以下方法会好一些：
#include <iostream> #include<sys/time.h> using namespace std; int delay(int time) { int i,j; for(i =0;i<time;i++) for(j=0;j<5000;j++) ; } int main () { struct timeval start; struct timeval end; unsigned long diff; gettimeofday(&start,NULL); delay(10); gettimeofday(&end,NULL); diff = 1000000 * (end.tv_sec-start.tv_sec)+ end.tv_usec-start.tv_usec; printf("thedifference is %ld\n",diff); return 0; }
