Validating an if-condition with bitwise operators

Question

I am facing a problem in dealing with basic if else statement in C#.

I have two variables of type uint. I need to check whether the first variable is in the range of the second one. Also, the first variable can have value null. The output comes up fine in case of i put some value for the first value. But the desired output fails in case I put null in the first variable

I did it in this manner.

using System;

public class Test
{
    public static void Main()
    {
        uint var1 = 0x00000000;
        uint var2 = 0x0ffffffa;
        if (!((var1 == null) || (((var1 != null) && (var1 & var2)) > 0)))
        Console.WriteLine ("no");
        else
        Console.WriteLine ("yes");
    }
}

The code when the output is coming as no is :

using System;

public class Test
{
    public static void Main()
    {
        uint var1 = 0x00000000;
        uint var2 = 0x0ffffffa;
        if (!(((var1 != null) && ((var1 & var2) > 0)) || (var1 == null)))
        Console.WriteLine ("no");
        else
        Console.WriteLine ("yes");
    }
}

But the output is coming as "no". Where am I going wrong?

I want a 'yes' as an output. I need to check for the first variable. If it is null then fine, if not, then whether it is in the range of the second variable, if it is, then also fine

`uint` is a value type and thus it can't be `null`. You have two redundant conditions in your if statement. — Sriram Sakthivel, Apr 23 '15 at 06:51
Probably, you want `var1 == 0` not `var1 == null`? Or you have to change `var1` type to something like `uint? var1 = 0x00000000;` — Dmitry Bychenko, Apr 23 '15 at 07:01
perhaps [this](https://dotnetfiddle.net/pM8qhT) will make it more clear for you. Do notice the two warnings that Sriram mentioned (i.e. uint cannot be null) — default, Apr 23 '15 at 07:17

score 0 · Answer 1 · answered Apr 23 '15 at 06:52

0

I'm confused as to what the question is here. You've initialized the variables, so they can't be null, you've used an OR logical operand so the statement will short-circuit when it evaluates the first term and finds it to be true.

answered Apr 23 '15 at 06:52

Slothrop

142
7

4

it feels to me like this should be a comment. You are not answering the question. – default Apr 23 '15 at 06:56
If the question is why "no" is being returned, then it is. – Slothrop Apr 23 '15 at 07:00
I want a 'yes' as an output. I need to check for the first variable. If it is null then fine, if not, then whether it is in the range of the second variable, if it is, then also fine. – Ayesha Gupta Apr 23 '15 at 07:05

Validating an if-condition with bitwise operators

1 Answers1