clock time times

1. clock，windows下的time一样， 也和 linux下的times一样

2. clock返回clock_t型，其实就是长整型

3. clock和times返回的单位是滴答

4. 滴答根据不同的系统，和不同的标准而不同

    The clock() function returns the processor time since the program started, or -1 if that information is unavailable. To convert the return value to seconds, divide it by CLOCKS_PER_SEC.(windows)

    times 和 clock都收用来计算cpu时间。times函数的返回值是进程迄今为止的存活时间。所有时间都是以“滴答”为单位的，linux系统下，函数 sysconf(_SC_CLK_TCK)可获得所运行系统每秒的滴答数。

clock和time的返回值都是long型

typedef long clock_t;

[cpp] view plaincopyprint?

1. //windows 
2. #include <stdio.h> 
3. #include <time.h> 
4.  
5.  
6. int main() 
7. { 
8.     printf("%ld\n", CLOCKS_PER_SEC); 
9.     return 0; 
10. } 

//windows#include <stdio.h>#include <time.h>int main(){printf("%ld\n", CLOCKS_PER_SEC);return 0;}

输出结果为：1000

[cpp] view plaincopyprint?

1. //Ubuntu 
2. #include <stdio.h> 
3. #include <unistd.h> 
4. #include <sys/times.h> 
5.  
6. int main(int argc,char* argv[]) 
7. { 
8.         int sec_per_dida = sysconf( _SC_CLK_TCK); 
9.         printf("%d\n", sec_per_dida); 
10.     return 0; 
11. } 

//Ubuntu#include <stdio.h>#include <unistd.h>#include <sys/times.h>int main(int argc, char* argv[]){int sec_per_dida = sysconf( _SC_CLK_TCK);printf("%d\n", sec_per_dida);return 0;}
输出结果为：100

time的例子：

[cpp] view plaincopyprint?

1. #include <stdio.h> 
2. #include <windows.h> 
3. #include <time.h> 
4.  
5. int main() 
6. { 
7.     long beg; 
8.     long end; 
9.     beg = time(0); 
10.     Sleep(5000); 
11.     end = time(0); 
12.     printf("%ld\n", end - beg); 
13.      
14.     return 0; 
15. } 

#include <stdio.h>#include <windows.h>#include <time.h>int main(){long beg;long end;beg = time(0);Sleep(5000);end = time(0);printf("%ld\n", end - beg);return 0;}
输出结果为5，可知time返回的单位是滴答。