Classes and Pre and Post Conversions
/*
A Programmer's Introduction to C# (Second Edition)
by Eric Gunnerson
Publisher: Apress L.P.
ISBN: 1-893115-62-3
*/
// 24 - User-Defined Conversions\Classes and Pre and Post Conversions
// copyright 2000 Eric Gunnerson
using System;
using System.Text;
public class ClassesandPreandPostConversions
{
public static void Main()
{
// implicit conversion section
RomanNumeralAlternate roman;
roman = new RomanNumeralAlternate(55);
BinaryNumeral binary = roman;
// explicit conversion section
BinaryNumeral binary2 = new BinaryNumeral(1500);
RomanNumeralAlternate roman2;
roman2 = (RomanNumeralAlternate) binary2;
}
}
class RomanNumeral
{
public RomanNumeral(short value)
{
if (value > 5000)
throw(new ArgumentOutOfRangeException());
this.value = value;
}
public static explicit operator RomanNumeral(
short value)
{
RomanNumeral retval;
retval = new RomanNumeral(value);
return(retval);
}
public static implicit operator short(
RomanNumeral roman)
{
return(roman.value);
}
static string NumberString(
ref int value, int magnitude, char letter)
{
StringBuilder numberString = new StringBuilder();
while (value >= magnitude)
{
value -= magnitude;
numberString.Append(letter);
}
return(numberString.ToString());
}
public static implicit operator string(
RomanNumeral roman)
{
int temp = roman.value;
StringBuilder retval = new StringBuilder();
retval.Append(RomanNumeral.NumberString(ref temp, 1000, 'M'));
retval.Append(RomanNumeral.NumberString(ref temp, 500, 'D'));
retval.Append(RomanNumeral.NumberString(ref temp, 100, 'C'));
retval.Append(RomanNumeral.NumberString(ref temp, 50, 'L'));
retval.Append(RomanNumeral.NumberString(ref temp, 10, 'X'));
retval.Append(RomanNumeral.NumberString(ref temp, 5, 'V'));
retval.Append(RomanNumeral.NumberString(ref temp, 1, 'I'));
return(retval.ToString());
}
public static implicit operator BinaryNumeral(RomanNumeral roman)
{
return(new BinaryNumeral((short) roman));
}
public static explicit operator RomanNumeral(
BinaryNumeral binary)
{
return(new RomanNumeral((short)(int) binary));
}
private short value;
}
class BinaryNumeral
{
public BinaryNumeral(int value)
{
this.value = value;
}
public static implicit operator BinaryNumeral(
int value)
{
BinaryNumeral retval = new BinaryNumeral(value);
return(retval);
}
public static implicit operator int(
BinaryNumeral binary)
{
return(binary.value);
}
public static implicit operator string(
BinaryNumeral binary)
{
StringBuilder retval = new StringBuilder();
return(retval.ToString());
}
private int value;
}
class RomanNumeralAlternate : RomanNumeral
{
public RomanNumeralAlternate(short value): base(value)
{
}
public static implicit operator string(
RomanNumeralAlternate roman)
{
return("NYI");
}
}
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