C :

#include <stdio.h>
int main(void)
{
	int a,n=8,i=0,x[100];
	scanf("%d",&a);
	for (i=0;;i++)
	{
		if (a>=n)
		{
			x[i]=a%n;
			a=a/n;
		}
		else 
		break;
	}
	printf("%d",a);
	i--;
	for(;i>=0;i--)
	{
		printf ("%d",x[i]);
	}
	return 0;
}

C++ :

#include <stdio.h>
int a[100000];
int main()
{
	int n;
	while(scanf("%d",&n)!=EOF)
	{
		int i=0;
		while(n)
		{
			a[i++]=n%8;
			n/=8;
		}
		for(int j=i-1;j>=0;j--)
		printf("%d",a[j]);
		printf("\n");
	}
	return 0;
}

Pascal :

var x,i,j:longint;
    a:array[1..99999]of longint;
begin
  readln(x);
  repeat
  inc(j);
  a[j]:=x mod 8;
  x:=x div 8;
  until x=0;
  for i:=j downto 1 do
  write(a[i]);
end.

Java :

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		

		Scanner cin = new Scanner(System.in);
		int a;
		String result;
		while (cin.hasNext()) {
			a = cin.nextInt();
			
			System.out.println(Integer.toOctalString(a));
		}
	}
}