输入某年,月,日,判断其在一年中是第几天.

#include <stdio.h>
int main(){
    int year ,month,day;
    int theday = 0;
    int legality = 1;
    scanf("%d%d%d",&year,&month,&day);
    if ((year%4==0&&year%100!=0)||year%400==0)
       switch (month)
       {
       case 1:
        if(day >= 0 && day <=31) theday += 0 ;
        else legality = 0;
           break;
        case 2:
            if(day >= 0 && day <=29) theday += 31 ;
        else legality = 0;
           break;

        case 3:
           if(day >= 0 && day <=31) theday += 60 ;
        else legality = 0;
           break;
        case 4:
            if(day >= 0 && day <=30) theday += 91 ;
        else legality = 0;
           break;
        case 5:
           if(day >= 0 && day <=31) theday +=121 ;
        else legality = 0;
           break;
        case 6:
           if(day >= 0 && day <=30) theday +=152 ;
        else legality = 0;
           break;
        case 7:
           if(day >= 0 && day <=31) theday += 182;
        else legality = 0;
           break;
        case 8:
            if(day >= 0 && day <=31) theday += 213 ;
        else legality = 0;
           break;
        case 9:
           if(day >= 0 && day <=30) theday += 244 ;
        else legality = 0;
           break;
        case 10:
           if(day >= 0 && day <=31) theday += 274 ;
        else legality = 0;
           break;
        case 11:
           if(day >= 0 && day <=30) theday += 305;
        else legality = 0;
           break;
        case 12:
           if(day >= 0 && day <=31) theday +=335 ;
        else legality = 0;
           break;
       default:
       legality = 0;
           break;
       }
       
   else if(!((year%4==0&&year%100!=0)||year%400==0))
         switch (month)
       {
       case 1:
           if(day >= 0 && day <=31) theday += 0 ;
        else legality = 0;
           break;
        case 2:
           if(day >= 0 && day <=28) theday +=31;
        else legality = 0;
           break;

        case 3:
           if(day >= 0 && day <=31) theday += 59;
        else legality = 0;
           break;
        case 4:
            if(day >= 0 && day <=30) theday +=90 ;
        else legality = 0;
           break;
        case 5:
           if(day >= 0 && day <=31) theday +=120 ;
        else legality = 0;
           break;
        case 6:
            if(day >= 0 && day <=30) theday += 151 ;
        else legality = 0;
           break;
        case 7:
           if(day >= 0 && day <=31) theday +=181 ;
        else legality = 0;
           break;
        case 8:
           if(day >= 0 && day <=31) theday += 212 ;
        else legality = 0;
           break;
        case 9:
            if(day >= 0 && day <=30) theday +=243 ;
        else legality = 0;
           break;
        case 10:
           if(day >= 0 && day <=31) theday +=273 ;
        else legality = 0;
           break;
        case 11:
           if(day >= 0 && day <=30) theday +=304 ;
        else legality = 0;
           break;
        case 12:
           if(day >= 0 && day <=31) theday +=334 ;
        else legality = 0;
           break;
       default:
       legality = 0;
           break;
       }
    
   if (legality == 0) printf("date error!");
   else
   {
     theday += day;
   printf("%d",theday);
   }
   

  
    return 0;
}