实验2 ljc

#include <stdio.h>
int main(){
    int n,m;
    printf("输入一个三位数");
    scanf("%d",&n);
    if(n>=0&&n<=9)
    printf("倒序正序相等");
   
    else if(n>=10&&n<=99){
    if(n%11==0)
    printf("倒序相等");
    else
    printf("倒序不等");
    }
    else if(n>=100&&n<=999){
    if(m=n%10*100+(n%100)/10*10+n/100==n)
    printf("倒序相等");
    else
    printf("倒序不等");
    }
    else
    printf("wrong\n");
    return 0; 
    
}

#include<stdio.h>

int main(){ 
int year,month,day,leapyear;
scanf("%d %d",&year,&month);
if(year<0||month<1||month>12)
{

    printf("输入的数据错误\n");
}

    leapyear=year%4==0&&year%100!=0||year%400==0;//是否为闰年
    
   if(month==1||month==3||month==5||month==7||month==8||month==10||month==12)
   
     printf("%d年%d月是31天\n",year,month);
       else if(month==4||month==6||month==9||month==11)
         printf("%d年%d月是30天\n",year,month);
             else if(leapyear==1)
             printf("%d年2月是29天",year);
                 else if(leapyear==0)
                    printf("%d年2月是28天",year);
   
    return 0; 
         
 } 

#include<stdio.h>
#include<stdlib.h>
int main()
{
	int score;
	scanf("%d",&score);
	if(score<0||score>100)
	{
		printf("输入数据错误\n");
		exit(0);
	}
	switch(score/10)
	{
		case 10:
		case 9:printf("优秀\n");break;
		case 8:printf("良好\n");break;
		case 7:printf("中等\n");break;
		case 6:printf("及格\n");break;
		default:printf("不及格\n");break;
	}
	return 0;
}