C++ :

#include <bits/stdc++.h>
using namespace std;

int main(){
	char a;
	cin>>a;
	if(a >= 'A' && a <= 'Y'|| a>='a' && a <= 'y'){
		a = a + 1;
	}else if(a == 'z'){
		a = 'a';
	}else if(a == 'Z'){
		a = 'A';
	}
	cout<<a;
}

Java :

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            String a=scanner.next(); //输入字符
            char[] b=a.toCharArray();  //转换为字符串
            for(int i=0;i<b.length;i++){
            if(b[i]>='a'&&b[i]<'z' || b[i]>='A'&&b[i]<'Z') //判断位置
                {
                    b[i]++;   //向前移位
                }
            if(b[i]=='z' || b[i]=='Z')
            {
                b[i]=(char) (b[i]-25); //从z转换为a
            }
            System.out.print(b[i]+" ");
            }
        }
    }
}

Python :

n=ord(input())+1
if n!=123 and n!=91:
    print(chr(n))
elif n==123:
    print('a')
else:
    print('A')