C利用time函數實現簡單的定時器

//定時器
#include <stdio.h>
#include <time.h>
#include <stdlib.h>

int main(int num, char* arg[]){
	//arg數組存放指針
	//printf("個數：%d 參數值1：%s 參數值2：%s 參數值：%s\n",num,arg[0],arg[1],arg[2]);
	if(num!=2){
		printf("必須輸入一個數字:%s\n",arg[0]);
		exit(1);
	}
	int duration = atoi(arg[1]);
	if(duration<=0) exit(1);
	//設置啟動時間
	time_t start, current;
	time(&start);
	printf("開始時間:%s	\n",ctime(&start));
	do{
		//設置當前時間
		time(&current);
	}while((current-start) != duration);
	printf("當前時間:%s	\n",ctime(&current));
		
	return 0;
}