C语言 <time.h> clock 函数

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  描述

  C库函数clock_t clock(void)返回自程序启动以来经过的时钟滴答数。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，此函数大约每72分钟将返回相同的值。
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  声明

  以下是clock函数的声明。

  
  clock_t clock(void)
  

  参数

  没有参数。
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  返回值

  此函数返回自程序启动以来经过的时钟滴答数。失败时，该函数返回值-1。

  示例

  以下示例显示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);
  }
  

  尝试一下

  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...