c# short if statement not working with int? (int=null)

Question

I am trying to shorten my code by using short-if:

int? myInt=myTextBox.Text == "" ? null : 
    Convert.ToInt32(myTextBox.Text);

But I'm getting the following error: Type of conditional expression cannot be determined because there is no implicit conversion between '' and 'int'

The following works:

int? myInt;
if (myTextBox.Text == "") //if no text in the box
   myInt=null;
else
   myInt=Convert.ToInt32(myTextBox.Text);

And if I replace the 'null' in integer (say '4') it also works:

int? myInt=myTextBox.Text == "" ? 4: 
    Convert.ToInt32(myTextBox.Text);

This is not a short if, but a ternary operator. – MarioDS Nov 11 '12 at 10:27 — MarioDS, Nov 11 '12 at 10:27

score 7 · Accepted Answer · answered Nov 11 '12 at 10:27

7

Try this instead :

int? myInt=myTextBox.Text == "" ? (int?)null : Convert.ToInt32(myTextBox.Text);

answered Nov 11 '12 at 10:27

Kundan Singh Chouhan

13,952
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3

You guys all don't give much about int.TryParse hm :) ? – Mohnkuchenzentrale Nov 11 '12 at 10:37

score 4 · Answer 2 · answered Nov 11 '12 at 10:34

4

What we need is to let the compiler know, that both parts of the if expression (if and else) are the same. And that's why C# contains the word default:

int? myInt=myTextBox.Text == "" 
   ? default(int?)
   : Convert.ToInt32(myTextBox.Text);

answered Nov 11 '12 at 10:34

Radim Köhler

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score 2 · Answer 3 · answered Nov 11 '12 at 10:33

2

My I suggest the following ?

int value;
int? myInt = ( int.TryParse(myTextBox.Text, out value ) ) ? value : default(int?);

answered Nov 11 '12 at 10:33

Mohnkuchenzentrale

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It also handles the case that the string cannot be converted to a int, like malformed strings or overflow – jefissu Apr 19 '22 at 11:28

score 0 · Answer 4 · answered Nov 11 '12 at 10:30

0

int? myInt=myTextBox.Text == "" ? (int?)null : 
    Convert.ToInt32(myTextBox.Text);

answered Nov 11 '12 at 10:30

Hamlet Hakobyan

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While this _may_ technically answer the question your answer would be significantly improved if you also state _why_ it does. – Ben Nov 11 '12 at 10:52

score 0 · Answer 5 · edited Dec 27 '16 at 10:32

0

int number =!string.IsNullOrEmpty(temp) ? Convert.ToInt32(temp) : (int?) null;

edited Dec 27 '16 at 10:32

Tushar

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answered Dec 27 '16 at 10:15

vijay joshi

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c# short if statement not working with int? (int=null)

5 Answers5