Null Coalescing operator in C-Sharp
It is used to pass default value if variable is null.
It is used for both value type and reference type variable.
It is used to avoid multiple if condition for checking null and returning non null value
In the following example value x is of value type is marked as nullable type and null value is assigned to variable “x”, while assigning value “x” to variable “y” we have checked for x is equal to null, if it is null then assign “100” or else assign value of “x”.
Value Type Example :
int? x = null;
int y = x ?? 100;
Console.WriteLine("y : " + y);
Output of the above program :
Reference Type Example :
In the following example value “selectedProduct ” is of refference type is marked as nullable type and null value is assigned to variable “selectedProduct ”, while assigning value “selectedProduct ” to variable “defaultProduct ” we have checked for selectedProduct is equal to null, if it is null then assign “Laptop” or else assign value of “selectedProduct”.
string selectedProduct = null;
string defaultProduct = selectedProduct ?? "Laptop";
Console.WriteLine("Product is : " + defaultProduct);