How to do ToString for a possibly null object

Question

Is there a simple way of doing the following   String s   myObj    null        myObj ToString      I know I can do the following  but I really consider it as a hack   String s        myObj    It would be great if Convert ToString   had a proper overload for this

User · Answer

I disagree with that this   String s   myObj    null        myObj ToString      is a hack in any way  I think it s a good example of clear code  It s absolutely obvious what you want to achieve and that you re expecting null   UPDATE    I see now that you were not saying that this was a hack  But it s implied in the question that you think this way is not the way to go  In my mind it s definitely the clearest solution

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Even though this is an old question and the OP asked for C  I would like to share a VB Net solution for those  who work with VB Net rather than C    Dim myObj As Object   Nothing Dim s As String   If myObj      ToString    myObj   42 s   If myObj      ToString     Unfortunatly VB Net doesn t allow the  -operator after a variable so myObj  ToString isn t valid  at least not in  Net 4 5  which I used for testing the solution   Instead I use the If to return an empty string in case myObj ist Nothing  So the first Tostring-Call return an an empty string  while the second  where myObj is not Nothing  returns  42

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Some  speed  performance tests summarizing the various options  not that it really matters  microoptimization  using a linqpad extension   Options  void Main         object objValue   null      test objValue       string strValue   null      test strValue         Define other methods and classes here void test string value        new Perf lt string gt               coallesce   n   gt   value    string Empty  ToString                 nullcheck   n   gt  value    null   string Empty   value ToString                 str Format   n   gt  string Format   0    value                str Concat   n   gt  string Concat value                string     n   gt       value               Convert   n   gt  Convert ToString value           Vs       void test object value        new Perf lt string gt               coallesce   n   gt   value    string Empty  ToString                 nullcheck   n   gt  value    null   string Empty   value ToString                 str Format   n   gt  string Format   0    value                str Concat   n   gt  string Concat value                string     n   gt       value               Convert   n   gt  Convert ToString value           Vs        Probably important to point out that Convert ToString      will retain a null string   Results  Object   nullcheck 1 00x 1221 ticks elapsed  0 1221 ms   in 10K reps  1 221E-05 ms per   coallesce 1 14x 1387 ticks elapsed  0 1387 ms   in 10K reps  1 387E-05 ms per   string   1 16x 1415 ticks elapsed  0 1415 ms   in 10K reps  1 415E-05 ms per   str Concat 1 16x 1420 ticks elapsed  0 142 ms   in 10K reps  1 42E-05 ms per   Convert 1 58x 1931 ticks elapsed  0 1931 ms   in 10K reps  1 931E-05 ms per   str Format 5 45x 6655 ticks elapsed  0 6655 ms   in 10K reps  6 655E-05 ms per    String   nullcheck 1 00x 1190 ticks elapsed  0 119 ms   in 10K reps  1 19E-05 ms per   Convert 1 01x 1200 ticks elapsed  0 12 ms   in 10K reps  1 2E-05 ms per   string   1 04x 1239 ticks elapsed  0 1239 ms   in 10K reps  1 239E-05 ms per   coallesce 1 20x 1423 ticks elapsed  0 1423 ms   in 10K reps  1 423E-05 ms per   str Concat 4 57x 5444 ticks elapsed  0 5444 ms   in 10K reps  5 444E-05 ms per   str Format 5 67x 6750 ticks elapsed  0 675 ms   in 10K reps  6 75E-05 ms per

User · Answer

Holstebroe s comment would be your best answer   string s   string Format   0    myObj     If myObj is null  Format places an Empty String value there   It also satisfies your one line requirement and is easy to read

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string Format   0    myObj     string Format will format null as an empty string and call ToString   on non-null objects  As I understand it  this is what you were looking for

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With an extension method  you can accomplish this   public static class Extension       public static string ToStringOrEmpty this Object value                return value    null        value ToString              The following would write nothing to the screen and would not thrown an exception           string value   null           Console WriteLine value ToStringOrEmpty

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It would be great if Convert ToString   had a proper overload for this    There s been a Convert ToString Object value  since  Net 2 0  approx  5 years before this Q was asked   which appears to do exactly what you want   http   msdn microsoft com en-us library astxcyeh v vs 80  aspx  Am I missing misinterpreting something really obvious here

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string s   String Concat myObj     would be the shortest way I guess and also have neglible performance overhead  Keep in mind though it wouldn t be quite clear for the reader of the code what the intention is

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C  6 0 Edit  With C  6 0 we can now have a succinct  cast-free version of the orignal method  string s   myObj  ToString       quot  quot    Or even using interpolation  string s     quot  myObj  quot    Original Answer  string s    myObj    String Empty  ToString     or string s    myObjc     quot  quot   ToString    to be even more concise  Unfortunately  as has been pointed out you ll often need a cast on either side to make this work with non String or Object types  string s    myObjc     Object  quot  quot   ToString   string s     Object myObjc     quot  quot   ToString    Therefore  while it maybe appears elegant  the cast is almost always necessary and is not that succinct in practice  As suggested elsewhere  I recommend maybe using an extension method to make this cleaner  public static string ToStringNullSafe this object value        return  value    string Empty  ToString

User · Answer

I had the same problem and solved it by simply casting the object to string  This works for null objects too because strings can be nulls  Unless you absolutely don t want to have a null string  this should work just fine   string myStr    string myObj     string in a object disguise or a null

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I might get beat up for my answer but here goes anyway  I would simply write string s    quot  quot  if  myObj    null       x   myObj toString       Is there a payoff in terms of performance for using the ternary operator  I don t know off the top of my head  And clearly  as someone above mentioned  you can put this behavior into a method such as safeString myObj  that allows for reuse

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actually I didnt understand what do you want to do  As I understand  you can write this code another way like this  Are you asking this or not  Can you explain more       string s   string Empty      if  string IsNullOrEmpty myObj             s   myObj ToString

[c#] How to do ToString for a possibly null object?

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