C :

fanxu(str1)  
char str1[100];  
{int i,t,j;  
char str2[100];strcpy(str2,str1);  
t=strlen(str1);  
for(i=0,j=t-1;j>-1;i++,j--)  
str1[i]=str2[j];
str1[i--]=0;
}  

int main()  
{char str0[100];  
scanf("%s",str0);  
fanxu(str0);  
printf("%s",str0);  
 return 0;
}

C++ :

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

int main()
{
	char a[1000000];
	int i = -1;
	char buf;
	for ( ; cin >> buf ; ) {
		a[++i] = buf;
		a[i+1] = '\0';
	}
	for ( ; i>=0 ; i--) {
		cout << a[i];
	}
	//_getch();
	return 0;
}

Java :

import java.util.Scanner;
import java.lang.StringBuilder;

public class Main {


	public static void main(String[] args) {
		Scanner sca=new Scanner(System.in);
		String str1=sca.next(); 	
		String str2=reverse3(str1);
		System.out.print(str2);

	}
	 public static String reverse3(String s) {
		 
		   char[] array = s.toCharArray();
		 
		   String reverse = "";
		 
		   for (int i = array.length - 1; i >= 0; i--)
		 
		    reverse += array[i];		   
		 
		   return reverse;
		  }


}

Python :

a = map(lambda x:(x), raw_input().split())[0]
print a[-1:0:-1]+a[0]