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A little game of guessing...

October 14, 2009 20:23 by author

Andrei Rinea

Let's say I have this block of C# code that compiles

if (someVariable == true)

{

// do something

}

but in a haste to optimize the code I change it into :

if (someVariable)

{

// do something

}

and suddenly my code does not compile anymore.

WHAT TYPE COULD someVariable HAVE?! Please comment on what you think about this small riddle :)

ef24bbc6-6b9f-4b80-b573-5e10e8161324|6|3.0

Tags: riddle
Categories: .NET
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Comments

October 14. 2009 20:57

Cred ca "someVariable" este de tipul bool? (nullable bool).

Petre Bogdan Florin

October 14. 2009 20:59

It should be of type bool? (System.Nullable<bool>).
If you use nullable types, you should check them first if has value (.HasValue)

I am waiting you next riddle

Thank you,
George

George

October 15. 2009 00:58

"bool?"

Programatorul lui peste

October 15. 2009 01:39

My guess was a nullable bool ( I mean - what else could it be ? )

But I wasn't sure of the reason until I tested it. if takes a bool parameter , not a Nullable<bool>

sirrocco

October 15. 2009 02:38

bool? )

mtz

October 15. 2009 02:48

Two possibilities:

1. bool?

2. A class that overloads == operator, without overloading true and false operators , and without defining an implicit conversion to bool.

Ex:

using System;
class Program
{
    static void Main(string[] args)
    {
        Program p = null;
        if (p == false)
            Console.WriteLine("P e null");
        p = new Program();
        if (p == true)
            Console.WriteLine("P nu mai e null");

    }

    public static bool operator ==(Program p, bool value)
    {
        return (p != null) == value;
    }

    public static bool operator !=(Program p, bool value)
    {
        return (p == null) == value;
    }
}

Pop Catalin

October 15. 2009 03:26

Simpatic quiz-ul, mi-a placut!

Raspunsul este: someVariable este un nullable bool. Compararea someVariable == true trece pentru ca COMPARI un nullable bool cu un bool, pe cand in if(someVariable) compilatorul se asteapta ca someVariable sa fie bool iar operatorul de casting T?->T de pe Nullable<T> este EXPLICIT si nu IMPLICIT, din care cauza iti da eroare la compilare ca vrea sa faci cast explicit la bool in if.

Sunt si eu pasionat de quiz-uri C#, daca-ti face placere poti vizita categoria asta de pe blogul meu: blogs.ugidotnet.org/.../272.aspx?Show=All (sunt in italiana dar textul in general cred ca se intelege)

Adrian Florea

October 15. 2009 18:41

Ma bucur pentru toate raspunsurile primite
Intr-adevar in situatia reala din care am descoperit aceasta mica ghicitoare aveam un System.Nullable<bool> aka "bool?".

Ma bucur si ca v-a placut ghicitoarea

Andrei Rinea

October 16. 2009 19:08

Si mie mi-a placut !

Andrei Ignat

August 24. 2010 00:40

I know its my first post here, but ive been reading for a while and really enjoy it

Delphia Burlage

August 24. 2010 00:40

That is a really good writeup! I appreciate all the time you have put into it, thanks!

Carmine Brisby

September 3. 2010 06:09

Watsup, just wanted to simply drop a comment to state my opinion.I happend to be employed by a group that mandated us to fill out these types of test regularly, and must state that they are not as accurate as you'd think. I could care less about what the user above me stated because I know the truth. Anyways superb blog.

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September 4. 2010 03:07

Watsup, just wanted to simply drop a comment to say my two cents.I was formerly employed in a company that forced us to fill out those types of test regularly, and must say that they just don't live up to the hype. I could give a rats ass about what the person above me said because I know the truth. Anyways awesome blog.

test psicométrico

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