Four examples of the C language

Title: Enter a certain period of a day, this day is judgment day of the year?

Program analysis: March 5, for example, should put the first two months together, then add the five days that is the day of this year's special circumstances, enter the month and leap year added an extra day to be considered greater than 3 .

#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：2015,12,10
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");
}