clock_t clock(void)
描述 (Description)
C库函数clock_t clock(void)返回自程序启动以来经过的时钟周期数。 要获得CPU使用的秒数，您需要除以CLOCKS_PER_SEC。
在CLOCKS_PER_SEC等于1000000的32位系统上，此函数将大约每72分钟返回相同的值。
声明 (Declaration)
以下是clock（）函数的声明。
clock_t clock(void)
参数 (Parameters)
NA
返回值 (Return Value)
此函数返回自程序启动以来经过的时钟周期数。 失败时，该函数返回值-1。
例子 (Example)
以下示例显示了clock（）函数的用法。
#include <time.h>
#include <stdio.h>
int main () {
clock_t start_t, end_t, total_t;
int i;
start_t = clock();
printf("Starting of the program, start_t = %ld\n", start_t);
printf("Going to scan a big loop, start_t = %ld\n", start_t);
for(i=0; i< 10000000; i++) {
}
end_t = clock();
printf("End of the big loop, end_t = %ld\n", end_t);
total_t = (double)(end_t - start_t)/CLOCKS_PER_SEC;
printf("Total time taken by CPU: %f\n", total_t );
printf("Exiting of the program...\n");
return(0);
}
让我们编译并运行上面的程序，它将产生以下结果 -
Starting of the program, start_t = 0
Going to scan a big loop, start_t = 0
End of the big loop, end_t = 20000
Total time taken by CPU: 0.000000
Exiting of the program...
