时间函数示例

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

int main( void )
{
     time_t start, finish, now;
     struct tm *ptr;
     char *c, buf1[80];
     double duration;

     /* Record the time the program starts execution. */

     start = time(0);

     time(&now);

     /* Convert the time_t value into a type tm structure. */

     ptr = localtime(&now);

     /* Create and display a formatted string containing the current time. */

     c = asctime(ptr);
     puts(c);
     getc(stdin);

     /* use the strftime() function to create several different formatted versions of the time. */

     strftime(buf1, 80, "This is week %U of the year %Y", ptr);
     puts(buf1);
     getc(stdin);

     strftime(buf1, 80, "Today is %A, %x", ptr);
     puts(buf1);
     getc(stdin);

     strftime(buf1, 80, "It is %M minutes past hour %I.", ptr);
     puts(buf1);
     getc(stdin);

     /* Now get the current time and calculate program duration. */

     finish = time(0);
     duration = difftime(finish, start);
     printf("/nProgram execution time using time() = %f seconds.", duration);

     /* display program duration in hundredths of seconds using clock(). */

     printf("/nProgram execution time using clock() = %ld hundredths of sec.", clock());
     return 0;
}