求大佬指点

    /* 定义需要计算的日期 */
    int year = 2008;
    int month = 8;
    int day = 8;
    int sum;
    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: break;
    }
    sum=sum+day;
    if(month>=2&&(year%400==0||(year%4==0&&year%100!=0))
        sum++;
    else
    sum=sum;
    printf("%d年%d月%d日是该年的第%d天"，year,month,day,sum);
    return 0;
}