Null-coalescing operator in C#

You can use the null-coalescing operator (??) to provide a default value for a nullable type or reference type.

The null-coalescing operator returns the left-hand operand if it is not null, or the right-hand operand if the left-hand operand is null.

Here is an example of how to use the null-coalescing operator:

string s = null;
string s2 = s ?? "default value";  // s2 is "default value"

This is equivalent to the following code:

string s = null;
string s2;
if (s != null)
{
    s2 = s;
}
else
{
    s2 = "default value";
}

The null-coalescing operator is a shorthand way to provide a default value for a nullable or reference type. It can make your code more concise and easier to read.