#include<stdio.h>

int main(void)
{
         int years, m, day;
         scanf("%d %d\n", &years, &m);
         if(years%400 == 0 || (years%4 == 0 && years%400 !=0));
         {
                if(m == 2)    {
                               printf("day=29");
                              }
                else {
                              if(m ==4 || m == 6 || m==9 ||m==11);
                              {
                               printf("day=30");
                              }  
                else          {
                              printf("day=31");
                              }
                     }
         }
         else
         {
                if(m == 2)    {
                               printf("day=28");
                              }
                else {
                              if(m ==4||m==6||m==9||m ==11);
                              {                  
                               printf("day=30");
                              }  
                else          {
                              printf("day=31");
                              }
                     }

         }
         return 0;
}


报错说的是else 前面没有if；求各位大侠帮帮忙，题目是：
输入年份和月份判断这个月份的天数。

1.if{}
elseif{}
else{}
2.if{}
else{}
而且，else是和离它最近的if对应的，lz你写的嵌套是这样
if{}
else{}
else{}
不报错才怪

#include<stdio.h>

int main(void)
{
         int years, m, day;
         scanf("%d %d", &years, &m);
         if(years%400 == 0 || (years%4 == 0 && years%400 !=0))
         {
                if(m == 2)   
                {
                     printf("day=29");
                }
                else if(m ==4 || m == 6 || m==9 ||m==11)
                {
                           
                     printf("day=30");
                 }  
                else         
                {
                     printf("day=31");
                }
                     
         }
         else
         {
                if(m == 2)   
                {
                     printf("day=28");
                }
                else if(m ==4||m==6||m==9||m ==11)
                {
                          
                     printf("day=30");
                }  
                else         
                {
                     printf("day=31");
                }
                  

         }
         return 0;
}
if后面不用加分号！！

[ 本帖最后由 a646404908 于 2012-3-19 22:56 编辑 ]

很简单,你的IF语句后面多出了分号;

系统认为语句结束了

同上

多看看IF....ELSE.....用法

多谢各位大侠！！！感激涕零！！！

#include<stdio.h>

int main(void)
{
         int years, m, day=0;
         scanf("%d %d\n", &years, &m);
         if(years%400 == 0 || (years%4 == 0 && years%400 !=0))
         {
                if(m == 2)    {
                               printf("day=29");
                              }
                else {
                              if(m ==4 || m == 6 || m==9 ||m==11)
                              {
                               printf("day=30");
                              }  
                else          {
                              printf("day=31");
                              }
                     }
         }
         else
         {
                if(m == 2)    {
                               printf("day=28");
                              }
                else {
                              if(m ==4||m==6||m==9||m ==11)
                              {                  
                               printf("day=30");
                              }  
                else          {
                              printf("day=31");
                              }
                     }

         }
         return 0;
}
if后面多了分号，并且最好初始化day=0这样就一点错误都没有

呵呵观摩一下，If语句不加分号的哦