Linux下一个练习c源代码(毫秒级计时)

#ifdef HAVE_CONFIG_H
#include
#endif

#include
#include
#include
int main(int argc, char *argv[])
{
printf("Hello, world!\n");
struct timeva l tvafter,tvpre;
struct timezone tz;
int sum = 0;
int i=0;
gettimeofday (&tvpre , &tz);

for(i = 0; i < 100000000; i++)
{
sum += i;
}
gettimeofday (&tvafter , &tz);
printf("sum=%d 花费时间:%d\n",sum, (tvafter.tv_sec-tvpre.tv_sec)*1000+(tvafter.tv_usec-tvpre.tv_usec)/1000);
return EXIT_SUCCESS;