C :

#include<stdio.h>
int main()
{
    char a;
    while((a=getchar())!=EOF)
    {
        if(a=='\n')
        {
            printf("%c",a);
            continue;
        }
        if(a>='a'&&a<='z')
        {
            a++;
            if(a=='z'+1)          
                a='a';
            }
        printf("%c",a); 
    }    
}

C++ :

#include <iostream>
#include <stdio.h>
//#include <conio.h>
#include <string>
//#include <math.h>
using namespace std;

int main()
{
	string a;
	int i = 0;
	getline(cin,a);
	for ( ; i<a.length() ; i++) {
		if (isalpha(a.at(i)) && a.at(i) != 'z') {
			a.at(i)++;
		} else if (a.at(i) == 'z') {
			a.at(i) = 'a';
		}
	}
	cout << a;
	//_getch();
	return 0;
}

Java :

import java.util.Scanner;

public class Main {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner input = new Scanner(System.in);
		
		String s = input.nextLine();
		for(int i = 0 ; i < s.length(); i ++){
			if(s.charAt(i) > 96 && s.charAt(i) < 123){
				if(s.charAt(i) < 122){
					System.out.printf("%c",s.charAt(i)+1);
				}else{
					System.out.print('a');
				}
			}else{
				System.out.print(s.charAt(i));
			}
		}
		input.close();
	}
	
	

}

Python :

#a = map(lambda x:float(x), raw_input().split())
x = ''
a = raw_input()
for i in a:
    if i ==' ':
        x+=' '
        continue

    if i =='z':
        x+='a'
        continue
    if ord(i) >70:
        x+=chr(ord(i)+1)
    else:
        x+=i
print x