Class to return a value when it is being referred

I have a class with two strings in it.

I would like to return one string when ever the object is referred to.

Code snippet:

public class ABC
{
    public string A = "first";
    public string B = "second";
}

public class useABC
{
    ABC obj;

    if(obj == "first")
         Console.writeLine("True");
}

What should I do in my ABC class to print "True".

Thanks in ad开发者_JAVA技巧vance.

You can override the implicit or explicit operator. Here's an MSDN article.

Note that too many implicit overloads can lead to a confusing or hard to use class.

I think you are looking to override the equality operator (==). Here's how to do it: Remember you have to overload the operator in both orders. Also, the compiler requires that you overload != at the same time.

public class ABS
{
    public string A;
    public string B;

    public static bool operator ==(ABS obj, string val){return obj.A == val;}
    public static bool operator !=(ABS obj, string val){return obj.A != val;}
    public static bool operator ==(string val, ABS obj){return obj.A == val;}
    public static bool operator !=(string val, ABS obj){return obj.A != val;}
}

The following code returns true for both expressions:

ABS abs = new ABS();
abs.A = "What?";

Assert.IsTrue(abs == "What?"); // true
Assert.IsTrue("What?" == abs); // true

How about implementing IEquatable<string> such that you can write ABC.Equals("first").

public class ABS : IEquatable<string>
{
    string A, B;
    public bool Equals(string other)
    {
        return A.Equals(other) || B.Equals(other);
    }
}

and later

if( ABC.Equals("first") ) { Console.WriteLine("true"); }

Then you can also override the == operator, but it is not recommended for class types. Like with string it is recommended to use the .Equals() method to check for equality. Alternatively, you can just add a method bool Contains(string other) to check if string is in A or B.