why not alowing Int nullable null in ternary operator

Question

4.00/5 (1 vote)

See more:

Hi,

Please look at below code :-

C#

using System.IO;
using System;
class Program
{
    static void Main()
    {
        Console.WriteLine("Hello, World!");
        int? i;
        i = 0==1?1:(int?)null;   //why here I have to cast null to int nullable
        i = null;                //not here
    }
}

Question is on comments. Please explain. This is weird.

Posted 2-Jul-15 1:33am

harshal rajkotia

Add a Solution

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

OriginalGriff · Accepted Answer · 2015-07-02T01:46:00

Because 1 is not a nullable int, so if you write this:

C#

int? i = 0==1 ? 1 : null;

The compiler tries to return a Value type (1, integer, which can't be null) and a Reference type (null) and says "These aren't the same type, and there is no implicit conversion"

When you specify the type of the second value:

C#

int? i = 0==1 ? 1 : (int?) null;

It realises what you are trying to do because there is an implicit conversion from int to nullable int

Tomas Takac · Accepted Answer · 2015-07-02T02:01:00

Quote from MSDN[^]:
Either the type of first_expression and second_expression must be the same, or an implicit conversion must exist from one type to the other.

There is no implicit conversion from null to int or vice versa. There is however conversion from int to nullable int and from null to nullable int too.

C#

i = 0==1?1:null;       // int vs. null - doesn't work
i = 0==1?1:(int?)null; // int vs. int? - works
i = 0==1?(int?)1:null; // int? vs. null - works as well

why not alowing Int nullable null in ternary operator

2 solutions

Solution 1

Solution 2

Add your solution here

Preview 0