C语言小程序 计算第二天日期示例代码

输入一个日期，判断下一个日期是哪一天，如果日期输入错误，则调用Linux下的cal命令显示输入的月份复制代码 代码如下:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
int year, month, day;
const int day_30 = 30;
const int day_31 = 31;
int day_month_2 = 0;
char err_flag = 0;
void compute()
{
printf("输入年月日(1992-7-19)：");
scanf("%d-%d-%d",&year, &month, &day);
if((year%4==0 && year%100!=0) || (year%400==0))
{
day_month_2 = 29;
}
else
{
day_month_2 = 28;
}
if(month>=1 && month<=12)
{
if(month == 2)
{
if(day > day_month_2)
{
err_flag = 1;
}
else if(day == day_month_2)
{
month++;
day = 1;
}
else
{
day++;
}
}
else if(month==1 || month==3 || month==5 || month==7 ||
month==8 || month==10 || month==12)
{
if(day > day_31)
{
err_flag = 1;
}
else if(day == day_31)
{
month++;
day = 1;
}
else
{
day++;
}
}
else
{
if(day > day_30)
{
err_flag = 1;
}
else if(day == day_30)
{
month++;
day = 1;
}
else
{
day++;
}
}
if(month > 12)
{
year++;
month = 1;
}
}
else
{
err_flag = 1;
}
}
int main()
{
time_t now;
char ch, c;
char call_cal[30];
do
{
compute();
if(err_flag)
{
err_flag = 0;
printf("日期输入错误，调用cal命令查询%d年%d月：nn",year, month);
sprintf(call_cal, "/usr/bin/cal %d %d",month, year);
system(call_cal);
//system("clear");
while((c=getchar())!='n' && (c=getchar())!=EOF);
printf("是否重新输入(y/n)：");
}
else
{
printf("第二天为%d-%d-%d。n",year, month, day);
while((c=getchar())!='n' && (c=getchar())!=EOF);
printf("是否再次输入日期(y/n)：");
}
ch = getchar();
}
while(ch=='y' || ch=='Y' || ch=='n');
time(&now);
printf("Now is %s",ctime(&now));
puts("Having a goodday!");
return 0;
}