Перевод целых чисел,записанных в системе счисления с основание q(2<=q<=16) в систему с основанием p (2<=p<=16)

#include <vcl.h>
#pragma hdrstop
 
#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
}
//---------------------------------------------------------------------------
String DecToX(__int64 number, Byte radix)
{
  String result = "", alphabet = "0123456789ABCDEF";
  if (radix > 1 && radix <= alphabet.Length())
  {
    do
    {
      result = String(alphabet[number % radix + 1]) + result;
      number /= radix;
    }
    while (number > 0);
  }
  return result;
}
//---------------------------------------------------------------------------
__int64 XToDec(String number, Byte radix)
{
  String alphabet = "0123456789ABCDEF";
  __int64 result = 0, factor = 1;
  if (radix > 1 && radix <= alphabet.Length())
  {
    int count = 0;
    number = number.UpperCase();
    for (int i = number.Length(); i >= 1; i--)
      for (int j = 1; j <= radix; j++)
        if (number[i] == alphabet[j])
        {
          result += factor * (j - 1);
          factor *= radix;
          count++;
          break;
        }
    if (count < number.Length())
      result = 0;
  }
  return result;
}
//---------------------------------------------------------------------------
String perevod(String number, Byte from_radix, Byte to_radix)
{
  return DecToX(XToDec(number, from_radix), to_radix);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::ButtonClick(TObject *Sender)
{
  EditResult->Text = perevod(Trim(EditNumber->Text), StrToIntDef(EditFromRadix->Text, 10), StrToIntDef(EditToRadix->Text, 10));
}
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
 
#ifndef Unit1H
#define Unit1H
//---------------------------------------------------------------------------
#include <System.Classes.hpp>
#include <Vcl.Controls.hpp>
#include <Vcl.StdCtrls.hpp>
#include <Vcl.Forms.hpp>
//---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published:    // IDE-managed Components
    TEdit *EditNumber;
    TEdit *EditResult;
    TLabel *LabelNumber;
    TLabel *LabelResult;
    TEdit *EditFromRadix;
    TLabel *LabelFromRadix;
    TButton *Button;
    TEdit *EditToRadix;
    TLabel *LabelToRadix;
    void __fastcall ButtonClick(TObject *Sender);
private:    // User declarations
public:     // User declarations
    __fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif