The ?? operator in C# called null-coalescing operator is used to define a default value for a nullable value types and reference types. It returns the left-hand operand if it is not null and returns right-hand operand if it is null.
example
// ?? operator example
. int? x = null;
int y = x ?? –1;
// Here the value of y will be –1.
int i = GetValue() ?? default(int);
Assigns the return value of the method to i if return value is not null other wise it assigns default value
It can be used with reference type as follows
string s = GetStringValue(); // ?? also works with reference types. // Display contents of s, unless s is null, // in which case display "Unspecified". Console.WriteLine(s ?? "Unspecified");
