程序代码：

#include<stdio.h>
#define MAX 80
#define CHANGE 1
void main()
{
    char str[MAX];
    int i;
    printf("请输入:\n");
    gets(str);
    #if(CHANGE)
    {
        for(i=0;i<MAX;i++);
        {
            if(str[i]!='\0')
                if(str[i]>='a'&&str[i]<'z'||str[i]>='A'&&str[i]<='Z')str[i]+=1;
            else if(str[i]=='z'||str[i]=='Z')str[i]-=25;
           
        }
    }
    #endif
    printf("输入为:\n%s\n",str);
}