“StringPlusNull” (Solution)

Answer

False

Explanation

A text fragment from C# Language Specification, the “7.8.4 Addition operator” section:

“String concatenation:

string operator +(string x, string y);
string operator +(string x, object y);
string operator +(object x, string y);

These overloads of the binary + operator perform string concatenation. If an operand of string concatenation is null, an empty string is substituted. Otherwise, any non-string argument is converted to its string representation by invoking the virtual ToString method inherited from type object. If ToString returns null, an empty string is substituted.”

Thus:

((string)null + null + null) == ("" + null + null) ==
  (("" + null) + null) == (("" + "") + null) == ("" + null) ==
  ("" + "") == ""
"" != null

Links

• Microsoft Reference Source

• Mono 3.10.0 Source

Problem