Wednesday, September 10, 2014

C# – Shorten null check around foreach loops

This is another blog post filed under “So I can remember this for next time. If it helps you too, great!”

In C#, when looping over a collection where the collection object itself might be null, if the desired behavior is to just loop zero times if the collection object is null, typical code would be:

List<MyType> list = PopulateList(); // Some method that returns a List<MyType>, or null 
if (list != null) 
{ 
  foreach (MyType mt in list) 
  { 
    // Do stuff with mt... 
  }
}

Using the C# null-coalescing operator ??, the above code can be condensed to:

List<MyType> list = PopulateList(); // Some method that returns a List<MyType>, or null
foreach (MyType mt in list ?? Enumerable.Empty<MyType>) 
{ 
  // Do stuff with mt... 
}

In that second example, if list is non-null, then the foreach iterates over it as normal. If list is null, then the foreach iterates over an empty collection -- so zero iterations are performed.

No comments:

Post a Comment