C语言牛客基础题2

#include <stdio.h>
int main() {
   int a,b,c,d,x,y;
   scanf("%d %d %d %d",&a,&b,&c,&d);
   x = a>b?a:b;
   y = c>d?c:d;
   printf("%d",x>y?x:y);
    return 0;
}

#include <stdio.h>
int main() {
    char ch=0;
    while(scanf("%c",&ch)!=EOF)
    {
        if(ch >= 65 && ch <= 91)
        {
            printf("%c\n",ch + 32);
        }else if(ch >= 97 && ch<=123)
        {
            printf("%c\n",ch-32);
        }
    }
    return 0;
}

#include<stdio.h>
int main()
{
    char n = 0;
    while(scanf("%c",&n)!=EOF)
    {
        if(n>='A'&&n<='Z' || n>='a'&&n<='z')
        {
            printf("%c is an alphabet.\n",n);
        }
        else 
            printf("%c is not an alphabet.\n",n);
            getchar();
    }//连续读取字符，需要在之间加上getchar()”过滤“回车键，避免回车键被读取
    return 0;
}