Null fall-through and chaining C# with Example

The left-hand operand must be nullable, while the right-hand operand may or may not be. The result will be typed 
accordingly. 
Non-nullable 
int? a = null; 
int b = 3; 
var output = a ?? b; 
var type = output.GetType(); 
Console.WriteLine($"Output Type :{type}"); 
Console.WriteLine($"Output value :{output}"); 
Output: 
Type :System.Int32 
 

value :3 
View Demo 
Nullable 
int? a = null; 
int? b = null; 
var output = a ?? b; 
output will be of type int? and equal to b, or null. 
Multiple Coalescing 
Coalescing can also be done in chains: 
int? a = null; 
int? b = null; 
int c = 3; 
var output = a ?? b ?? c; 
var type = output.GetType(); 
Console.WriteLine($"Type :{type}"); 
Console.WriteLine($"value :{output}"); 
Output: 
Type :System.Int32 
value :3 
View Demo 
Null Conditional Chaining 
The null coalescing operator can be used in tandem with the null propagation operator to provide safer access to 
properties of objects. 
object o = null; 
var output = o?.ToString() ?? "Default Value"; 
Output: 
Type :System.String 
value :Default Value 
View Demo