#include<stdio.h> int main() { int year,month,day,sum,leap; printf("Please enter year,month,day (just like:2009,9,9)\n"); scanf("%d,%d,%d",&year,&month,&day); switch(month) {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("Enter wrong!Please enter right date.\n"); break; } sum=sum+day; if (year%4==0&&year%100!=0||year%400==0) leap=1; else leap=0; if(leap==1&&month>2) sum=sum+1; printf("It is the %dth day.",sum); return 0; }