時刻の構造体と時間差

#include <stdio.h>

typedef struct {
    int hour;
    int minute;
    int second;
} time;

int main(void)
{
    int diff;
    time t1,t2;
    printf("時刻1の時 分 秒を入力 >");
    scanf("%d %d %d",&t1.hour,&t1.minute,&t1.second);
    printf("時刻2の時 分 秒を入力 >");
    scanf("%d %d %d",&t2.hour,&t2.minute,&t2.second);

    diff = (t1.hour - t2.hour) * 3600 + (t1.minute - t2.minute) * 60 + (t1.second - t2.second);
    if(diff < 0) diff += 24 * 3600;
    printf("時間差は%d時間%d分%d秒です。\n", diff/3600,diff%3600/60,diff%60);

    return 0;
}