C语言 这一题最后要怎么写啊？

#include <stdio.h>
int isleap(int year);                   //判断是否闰年
int whatday(int month, int day);        //判断在普通年份下的天数。
main()
{
    int year,month,day,num;
    scanf("%d %d %d",&year,&month,&day);
    num=whatday(month,day);
    if(month>=3 && isleap(year)==1)     //如果过了二月份，而且是闰年
        num++;                          //那就再增加一天
    printf("%d\n",num);
}
@@1
@@1

#include<bits/stdc++.h>
bool leap(int year){
    if( (year%4==0 && year%100!=0) || year%400==0 ) return true;
    else return false;
}
int main(){
    int year,month,day;
    int leapm[12] = {31,29,31,30,31,30,31,31,30,31,30,31};
    int common[12] = {31,28,31,30,31,30,31,31,30,31,30,31};
    while(~scanf("%d %d %d",&year,&month,&day)){
        int days = 0;
        if(leap(year))
            for(int i=0;i<month-1;i++) days += leapm[i];
        else for(int i=0;i<month-1;i++) days += common[i];
        days += day;
        printf("%d\n",days);
    }
    return 0;
}

#include <stdio.h>
int main() 
 { 
    int day, month, year, sum, leap; 
    printf("\n请输入年、月、日,格式为:年,月,日(2015 12 10)\n");
    scanf("%d%d%d", &year, &month, &day); // 格式为:2019 05  10
    switch (month) // 先计算某月以前月份的总天数 
        { 
            case 1:sum = 0;break; 
            case 2:sum = 31;break;
            case 3:sum = 59;break; 
            case 4:sum = 90;break;
            case 5:sum = 120;break; 
            case 6:sum = 151;break; 
            case 7:sum = 181;break; 
            case 8:sum = 212;break; 
            case 9:sum = 243;break; 
            case 10:sum = 273;break;
            case 11:sum = 304;break; 
            case 12:sum = 334;break;
            default:printf("data error");break;
	 } 
	 sum = sum + day; // 再加上某天的天数 
	 if (year%400 == 0 || (year % 4 == 0 && year %100 != 0))
	   { // 判断是不是闰年 
	        leap = 1; 
	   } 
	 else
	   {
            leap = 0; 
	   } 
	 if (leap == 1 && month > 2) 
	   { // *如果是闰年且月份大于2,总天数应该加一天 
	        sum++; 
	   } 
    printf("这是这一年的第 %d 天。", sum);
    printf("\n"); 
    return 0;
}

这个好理解吧，前面列出12个月的天数，最后在判断是否是闰年，如果是 输入的月份大于2，天数多加1

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