overloading true and false operators?

[MrPolite]

uuh what the heck would that mean? if a class overloads true and false, what does it really mean?:D how would you use those operators for that class then?

(I'm an idiot as far as operator overloading is concerned, so please bear with me:D)

[nebulom]

Don't know really if we can overload it, provided that they have the same type (of type bool). :D Just go for a condition.

class test
{
bool boolean;
public test(bool boolean)
{
if(boolean) true_statement();
else false_statement();
}
void true_statement(){}
void false_statement(){}
}

:D

[MrPolite]

this is what I meant

public static bool operator true (myClass val)
{
return true;
}

[nebulom]

Oppss. :afrog:

Yes, you're right. Can't seem to find a good example why true/false operator is overloaded.

[nebulom]

Just found this (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/csref/html/vcwlkoperatoroverloadingtutorial.asp). Don't really understand it coz I don't really understand English well. :D But hopes this might have a use for you.

[MrPolite]

hmmmmmmmmmmmmmm
thanks, but I still dont understand it:D

[axion_sa]

Let's say you've created a class, and you want to perform value based comparisons between two instances (the default is reference comparisons) - you overload the ==, != and .Equals operators and methods to perform those comparisons.

[MrPolite]

hmm ok but this seems to be different. This is overriding TRUE and FALSE
public static bool operator true (myClass val)
{
return true;
} :confused:

[axion_sa]

Oh, sorry - misunderstood :p

From MSDN:

The DBBool struct below implements a three-valued logical type. The possible values of this type are DBBool.True, DBBool.False, and DBBool.Null, where the Null member indicates an unknown value. Such three-valued logical types are commonly used in databases.


using System;
public struct DBBool
{
// The three possible DBBool values.
public static readonly DBBool Null = new DBBool(0);
public static readonly DBBool False = new DBBool(-1);
public static readonly DBBool True = new DBBool(1);
// Private field that stores –1, 0, 1 for False, Null, True.
sbyte value;
// Private instance constructor. The value parameter must be –1, 0, or 1.
DBBool(int value) {
this.value = (sbyte)value;
}
// Properties to examine the value of a DBBool. Return true if this
// DBBool has the given value, false otherwise.
public bool IsNull { get { return value == 0; } }
public bool IsFalse { get { return value < 0; } }
public bool IsTrue { get { return value > 0; } }
// Implicit conversion from bool to DBBool. Maps true to DBBool.True and
// false to DBBool.False.
public static implicit operator DBBool(bool x) {
return x? True: False;
}
// Explicit conversion from DBBool to bool. Throws an exception if the
// given DBBool is Null, otherwise returns true or false.
public static explicit operator bool(DBBool x) {
if (x.value == 0) throw new InvalidOperationException();
return x.value > 0;
}
// Equality operator. Returns Null if either operand is Null, otherwise
// returns True or False.
public static DBBool operator ==(DBBool x, DBBool y) {
if (x.value == 0 || y.value == 0) return Null;
return x.value == y.value? True: False;
}
// Inequality operator. Returns Null if either operand is Null, otherwise
// returns True or False.
public static DBBool operator !=(DBBool x, DBBool y) {
if (x.value == 0 || y.value == 0) return Null;
return x.value != y.value? True: False;
}
// Logical negation operator. Returns True if the operand is False, Null
// if the operand is Null, or False if the operand is True.
public static DBBool operator !(DBBool x) {
return new DBBool(-x.value);
}
// Logical AND operator. Returns False if either operand is False,
// otherwise Null if either operand is Null, otherwise True.
public static DBBool operator &(DBBool x, DBBool y) {
return new DBBool(x.value < y.value? x.value: y.value);
}
// Logical OR operator. Returns True if either operand is True, otherwise
// Null if either operand is Null, otherwise False.
public static DBBool operator |(DBBool x, DBBool y) {
return new DBBool(x.value > y.value? x.value: y.value);
}
// Definitely true operator. Returns true if the operand is True, false
// otherwise.
public static bool operator true(DBBool x) {
return x.value > 0;
}
// Definitely false operator. Returns true if the operand is False, false
// otherwise.
public static bool operator false(DBBool x) {
return x.value < 0;
}
public override bool Equals(object obj) {
if (!(obj is DBBool)) return false;
return value == ((DBBool)obj).value;
}
public override int GetHashCode() {
return value;
}
public override string ToString() {
if (value > 0) return "DBBool.True";
if (value < 0) return "DBBool.False";
return "DBBool.Null";
}
}