程序代码：

/* Illustrates the modulus operator. */
/* Inputs a number of seconds, and converts to hours, */
/* minutes, and seconds. */

#include <stdio.h>

/* Define constants */

#define SECS_PER_MIN 60
#define SECS_PER_HOUR 3600

unsigned seconds, minutes, hours, secs_left, mins_left;

int main( void )
{
    /* Input the number of seconds */

    printf("Enter number of seconds (< 65000): ");
    scanf("%d", &seconds);

    hours = seconds / SECS_PER_HOUR;
    minutes = seconds / SECS_PER_MIN;
    mins_left = minutes % SECS_PER_MIN;
    secs_left = seconds % SECS_PER_MIN;

    printf("%u seconds is equal to ", seconds);
    printf("%u h, %u m, and %u s\n", hours, mins_left, secs_left);

    return 0;
}