C :

#include<stdio.h>
#define NO 0
#define OK 1
#define Stack_Size 50
typedef int StackElementType;
typedef struct 
{
StackElementType elem[Stack_Size];
int top;
}SeqStack;
void InitStack(SeqStack *S)
{
S->top=-1;
}
int Push(SeqStack *S,StackElementType x)
{
   if(S->top==Stack_Size)
       return(NO);
   else 
   {
S->top++;
S->elem[S->top]=x;
return(OK);
   }
}
int Pop(SeqStack *S,StackElementType *x)
{
   if(S->top==-1)
       return(NO);
   else
   {
*x=S->elem[S->top];
S->top--;
return(OK);
   }
}
int GetPop(SeqStack *S,StackElementType *x)
{
if(S->top==-1)
return(NO);
else
{
*x=S->elem[S->top];
return (OK);
}
}
void Converson(int N,int n,SeqStack S,int x)
{
InitStack(&S);
while(N>0)
{
x=N%n;
Push(&S,x);
N=N/n;
}
while(S.top>-1)
{
Pop(&S,&x);
printf("%d",x);

}

} 
void main()
{
SeqStack S;
int N,n,x;
scanf("%d%d",&N,&n);
Converson(N,n,S,x);
printf("\n");
}

C++ :

#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>
#define TRUE 1
#define FALSE 0
#define Stack_Size 50
#include <iostream>
using namespace std;
typedef int StackElementType; 
typedef struct		//初始化顺序栈
{
	StackElementType elem[Stack_Size];
	int top;
}SeqStack;
void InitStack(SeqStack *S)
{
	S->top=-1;
}
int Push(SeqStack *S,StackElementType x)	//顺序栈进栈
{
	if(S->top==Stack_Size-1)
		return(FALSE);
	S->top++;
	S->elem[S->top]=x;
	return(TRUE);
}
int Pop(SeqStack *S,StackElementType *x)//出栈
{
	if(S->top==-1)
		return(FALSE);
	else
	{
		*x=S->elem[S->top];
	S->top--;
		return(TRUE);
	}
}
int GetTop(SeqStack *S,StackElementType *x)	//顺序栈读栈顶元素
{
	if(S->top==-1)
		return(FALSE);
	else
	{
		*x=S->elem[S->top];
		return(TRUE);
	}
}
void StackOutput(SeqStack *S/*,StackElementType *x */)	//输出
{
	int i;
    for(i=0;i<S->top;i++)
	cout<<S->elem[i]<<endl;    
}

void Converson(int N,int n)		//进制转换
{	
	SeqStack S;
	InitStack(&S);
	int x;
	while(N>0)
	{
		x=N%n;
		Push(&S,x);
		N=N/n;
	}
while(S.top>-1)
	{
		Pop(&S,&x);
		cout<<x;
	}
}
int main()
{
	int N,n,x;
	cin>>N>>n;
	x=0;
	Converson(N,n);
  return 0;
}

Pascal :

var x,n,i,j:longint;a:array[1..100] of longint;
begin
readln(x,n);i:=0;
while x>0 do
begin
inc(i);
a[i]:=x mod n; x:=x div n;
end;
for j:=i downto 1 do
if a[j]>=10 then write(chr(a[j]+55))
else   write(a[j]);
writeln;
end.