C语言的两个工具函数

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1. 测试程序执行时间的函数

#include <stdio.h>#include <stdlib.h>#include <time.h>void sleep( clock_t wait );void main( void ){  long i = 60000000L;//6000 W  clock_t start, finish;  double duration;  /* Delay for a specified time. */  printf( "Delay for three seconds\n" );  sleep( (clock_t)3 * CLOCKS_PER_SEC );  printf( "Done!\n" );  /* Measure the duration of an event. */  printf( "Time to do %ld empty loops is ", i );  start = clock();  while( i-- )  ;  finish = clock();  duration = (double)(finish - start) / CLOCKS_PER_SEC;  printf( "%2.2f seconds\n", duration );}/* Pauses for a specified number of milliseconds. */void sleep( clock_t wait ){  clock_t goal;  goal = wait + clock();  while( goal > clock() )  ;}

2. 用于随机生成数组并存入文件，以便多个函数调用

#include <stdio.h>#include <stdlib.h>#include <time.h>#define DATASIZE 10000int main(int argc, char ** argv){      const char * file_name = "out.dat";  FILE * fp = fopen(file_name, "wb");//必须放在其他变量的定义之前  int i, a, b[DATASIZE];  srand( time(NULL) );  for(i=0; i<DATASIZE; i++)  {  a=rand()%100;  fwrite(&a, sizeof(int), 1, fp);  }  fclose(fp);      fp = fopen(file_name, "rb");      fread(&b, sizeof(int), DATASIZE, fp);        for(i=0; i<10; i++)  printf("%d  ", b[i]);  printf("\n");      return 0;}

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