万年历（1990之后）

1. 万年历（1990之后）

#include<stdio.h>
int main()
{
    int year,month;
    int i=1900;
    int sum=0;
    int a[13]={0,31,28,31,30,31,30,31,31,30,31,30,31};
    printf("please input year and month:"); 
    scanf("%d%d",&year,&month);
    if(year<1990 || (month<1 || month>12))
    {
        printf("input error");
    }   
    else
    {

        while(i<year)
        {
            if((i%4==0 && i%100!=0) || i%400==0)
            {
                 sum+=366;
            }    
            else
            {
                 sum+=365;
            }
            i++;
        }
        if((year%4==0 && year%100!=0) || year%400==0)
        {
            a[2]=29;
        }
        else
        {
            a[2]=28;

        }
        printf("%d\n",a[2]);
        int j=1;
        while(j<month)
        {
            sum=sum+a[j];
            j++;
        }

    }
    
    int week=sum%7;
    //printf("week=%d\n",week);
    week=(week+1)%7;
    printf("\t\t\t%d/%d\n",year,month);
    printf("Sun\tMon\tTues\tWed\tThur\tFri\tSat\n");
    int colum=0;
     i=1;
     int b=a[month];
    while (i<=week)
    {
        printf("\t");
        i++;
        colum++;
    }
     i=1;
    while(i<=b)
    {
        printf("%2d\t",i);
        colum++;
        if(colum%7==0)
        {
            printf("\n");
        }
        i++;
    }
    printf("\n");
    return 0;
}