Is there a simple way to write only not null parameters with string.format

Question

Instead of writing something like this

if(param!=null){
   string message = String.Format("Time: {0}, Action: {1}, Param: {2}" time,someaction,param)
}else{                                                                   
string message = String.Format("Time:{0},Action:{1}" time,someaction);

can i write

string message = String.Format(("Time: {0}, Action: {1}, Param: {2}!=null" time,someaction,param)

score 2 · Answer 1 · answered Apr 28 '17 at 08:34

No, but you can write this

string message = param != null 
    ? String.Format("Time: {0}, Action: {1}, Param: {2}" time, someaction, param)
    : String.Format("Time: {0}, Action: {1}" time, someaction);

It's called ternary operator and is a nice way to shorten if else statements.

In C# 6 you can shorten your String.Format as well; for example

$"Time: {time}, Action: {someaction}, Param: {param}"

instead of

String.Format("Time: {0}, Action: {1}, Param: {2}" time, someaction, param)

score 1 · Answer 2 · answered Apr 28 '17 at 08:38

1

You can use something like :

string message = String.Format("Time: {0}, Action: {1}{2}",
    time,
    someaction,
    param ? String.Format(", Param: {0}",param) : ""  
);

answered Apr 28 '17 at 08:38

napuzba

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Mong Zhu · Answer 3 · 2017-04-28T08:40:17.327

1

Actually there is:

string message = String.Format("Time: {0}, Action: {1}, " + 
                 (param != null ? " Param: {2}" : string.Empty), 
                  time, someaction, param);

It looks a little unreadable though.

The idea is basically to add a further string and placeholder for the third parameter into the string only if the condition is met.

edited Apr 28 '17 at 08:40

answered Apr 28 '17 at 08:38

Mong Zhu

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score 1 · Answer 4 · answered Apr 28 '17 at 08:42

Very similar to the other answers but you can try this as well:

string message = String.Format("Time: {0}, Action: {1}{2}",time,someaction,param==null?"":
                 String.Format(", param : {0}",param) );

Here we are adding the param as another formatted string, and are included to the actual output only is the item is not null. Hope that this Example will explain things clearer than my words. Please take a look

TheGeneral · Accepted Answer · 2017-04-28T10:04:38.687

1

Or this is nice and tidy if you are using a vs 2015+ / c#6 Coalesce with string interpolation

var message = $"Time: {time}, Action: {someaction}" + (param != null ? $", Param: {param}" : "");

edited Apr 28 '17 at 10:04

answered Apr 28 '17 at 08:54

TheGeneral

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var message = $"Time: {time}, Action: {someaction}" + (param != null ? $", Param: {param}" : ""); – DraganB Apr 28 '17 at 09:57
1

i needed to add brackets after +, but thanks for this classy idea :) – DraganB Apr 28 '17 at 09:58
1

Typed on my phone. Glad it helped – TheGeneral Apr 28 '17 at 09:59

Is there a simple way to write only not null parameters with string.format

5 Answers5