Калькулятор принимает только целые числа для ввода

//---------------------------------------------------------------------------
 
#include <vcl.h>
#include <string>
#include "Math.h"
#pragma hdrstop
 
#include "Unit3.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm3 *Form3;
float a, b;
float res;
//---------------------------------------------------------------------------
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 XtoY(String number, Byte from_radix, Byte to_radix)
{
return DecToX(XToDec(number, from_radix), to_radix);
}
//-------------------------------------------------------------------------—