C # A new operator provided

The "null coalescing" operator is a new operator provided by C # that provides the ability to determine whether the operand on the left is null, and if so, the result is the operand on the right, and Non-null returns the operand on the left.

We can look at the following examples to see how this operator is used:

string message = "Hello World";
string result = message ?? "null";
　//这里的result的内容是 Hello World

Look at the following example:

string message = null;
string result = message ?? "It's null";
　//在这里result的内容将是 It's　null