Nuno Silva

Recursive operator == because of a null

I came up with a simple error that can make lose some hours around something has simple has an operator.

imagine that you have the following operator definition:

public static bool operator ==(Player c1, Player c2) {
	if( c1 == null && c2 == null ) {
		return true;
	}
	if ( c1 == null || c2 != null ) {
		return false;
	}
	return c1.Id == c2.Id;
}

The above code should work in a normal situation. But not in a situation where we use the operator inside it’s own definition. The code will enter a recursive state and it will eventually generate a Stack Overflow Exception.

So, in order to avoid the usage of the operator == inside it’s definition, you can use the alternative:

the Equals Type method inherit from object.

The following code demonstrates the correct implementation of the operator ==:

public static bool operator ==(Player c1, Player c2) {
	if( Equals(c1,null) && Equals(c2,null) ) {
		return true;
	}
	if ( Equals(c1, null) || Equals(c2, null) ) {
		return false;
	}
	return c1.Id == c2.Id;
}

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