As the title says. Related to this question.
Why does the following code not work? It seems reasonable logically.
string foo = \'a\' + \'b\'; // Fail
What you are really looking for is this:
string foo = String.Concat('a', 'b');
Which is what the compiler does with the '+' operator on strings anyways.
This is about twice as fast as any String.Format operation.
String.Format