C :

#include<stdlib.h>
#include<stdio.h>
void mole(int a,int b)
{if(a/b==0)printf("%d",a%b);
else {mole(a/b,b);printf("%d",a%b);}
     }
int main()
{
    int x;
    scanf("%d",&x);
    mole(x,8);
return 0;}

C++ :

#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
using namespace std;
void dg(int);
int main()
{
	int n;
	cin>>n;
	dg(n);
	cout<<endl;
	return 0;
}
void dg(int i)
{
	int j,k;
	j = i % 8;
	k = i / 8;

	if (k != 0) dg(k);
	cout<<j;
}

Pascal :

program pyy;
var
  a:integer;
procedure to8(n:integer);
begin
    if n>=1
      then to8(n div 8)
      else exit;
    write(n mod 8);
end;

begin
    readln(a);
    to8(a);
    readln;
end.