小编Mic*_*ick的帖子

在阅读了这篇关于经过时间的文章之后,我写了一个简单的代码来计算循环的执行时间:

#include <stdio.h>
#include <sys/time.h>

int main (int argc, char** argv) {
    struct timeval, tvalBefore, tvalAfter;

    gettimeofday (&tvalBefore, NULL);
    int i =0;
    while ( i < 1000) {
        i ++;
    }

    gettimeofday (&tvalAfter, NULL);

    printf("Time in microseconds: %0.3f microseconds\n",
            (float)(tvalAfter.tv_sec - tvalBefore.tv_sec) 
          )
    return 0;
}

clang编译器给我以下错误:

print_time.c:7:16: error: expected identifier or '('
        struct timeval, *tvalBefore, *tvalAfter;
                      ^
print_time.c:13:17: error: use of undeclared identifier 'tvalBefore'
        gettimeofday (&tvalBefore, NULL);
                       ^
print_time.c:19:17: error: use of undeclared identifier 'tvalAfter' …