One liner for If string is not null or empty else

Question

I usually use something like this for various reasons throughout an application:

if (String.IsNullOrEmpty(strFoo))
{
     FooTextBox.Text = "0";
}
else
{
     FooTextBox.Text = strFoo;
}

If I'm going to be using it a lot I will create a method that returns the desired string. For example:

public string NonBlankValueOf(string strTestString)
{
    if (String.IsNullOrEmpty(strTestString))
        return "0";
    else
        return strTestString;
}

and use it like:

FooTextBox.Text = NonBlankValueOf(strFoo);

I always wondered if there was something that was part of C# that would do this for me. Something that could be called like:

FooTextBox.Text = String.IsNullOrEmpty(strFoo,"0")

the second parameter being the returned value if String.IsNullOrEmpty(strFoo) == true

If not does anyone have any better approaches they use?

I would not change your code, except to make `NonBlankValueOf` static. Don't rely on something that C# might provide - the method `NonBlankValueOf` has a specific meaning to your app, and you control that meaning. For example, what if you needed to change "0" to "1" someday? — default.kramer, Mar 27 '13 at 13:54

score 164 · Accepted Answer · edited Nov 09 '20 at 04:27

164

There is a null coalescing operator (??), but it would not handle empty strings.

If you were only interested in dealing with null strings, you would use it like

string output = somePossiblyNullString ?? "0";

For your need specifically, there is the conditional operator bool expr ? true_value : false_value that you can use to simplify if/else statement blocks that set or return a value.

string output = string.IsNullOrEmpty(someString) ? "0" : someString;

edited Nov 09 '20 at 04:27

Pang

9,564
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answered Mar 27 '13 at 13:49

Anthony Pegram

123,721
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2

+1 for a good example of when to use null coalesc, although the OP may need it to catch empty string in his/her case. – Devin Burke Mar 27 '13 at 13:50
Is there a way to do this 2nd thing (string output = string.IsNullOrEmpty(someString) ? "0" : someString;), but if 'someString' is an expression, then capture the result of that expression and return it in the end? I haven't found anything on this yet, but find it would be very useful. – mochsner May 07 '21 at 07:01

score 16 · Answer 2 · answered Mar 27 '13 at 13:49

16

You could use the ternary operator:

return string.IsNullOrEmpty(strTestString) ? "0" : strTestString

FooTextBox.Text = string.IsNullOrEmpty(strFoo) ? "0" : strFoo;

answered Mar 27 '13 at 13:49

Jim Mischel

131,090
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ssilas777 · Answer 3 · 2015-11-06T04:57:56.130

11

You can write your own Extension method for type String :-

 public static string NonBlankValueOf(this string source)
 {
    return (string.IsNullOrEmpty(source)) ? "0" : source;
 }

Now you can use it like with any string type

FooTextBox.Text = strFoo.NonBlankValueOf();

edited Nov 06 '15 at 04:57

answered Mar 27 '13 at 13:52

ssilas777

9,672
4
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score 8 · Answer 4 · answered Mar 27 '13 at 13:49

8

This may help:

public string NonBlankValueOf(string strTestString)
{
    return String.IsNullOrEmpty(strTestString)? "0": strTestString;
}

answered Mar 27 '13 at 13:49

Hossein Narimani Rad

31,361
18
86
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score 0 · Answer 5 · answered Sep 12 '14 at 21:19

0

Old question, but thought I'd add this to help out,

#if DOTNET35
bool isTrulyEmpty = String.IsNullOrEmpty(s) || s.Trim().Length == 0;
#else
bool isTrulyEmpty = String.IsNullOrWhiteSpace(s) ;
#endif

answered Sep 12 '14 at 21:19

dathompson

65
3

score 0 · Answer 6 · answered Nov 12 '20 at 16:59

0

You can achieve this with pattern matching with the switch expression in C#8/9

FooTextBox.Text = strFoo switch
{
    { Length: >0 } s => s, // If the length of the string is greater than 0 
    _ => "0" // Anything else
};

answered Nov 12 '20 at 16:59

Kevin Smith

13,746
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One liner for If string is not null or empty else

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