In C# 6.0, What Is The Meaning Of The Question Mark And Dot Operator “?.”?

The question mark and dot operator ?. is known as the null-conditional or null-propagating operator introduced in C# 6.0. It is used to simplify null checking when accessing members of an object or invoking methods on it.

Before the introduction of ?. operator, you had to perform null checks manually to prevent null reference exceptions. For example, consider the following code:

if (obj != null)
{
    var result = obj.SomeMethod();
}

With the ?. operator, you can rewrite the above code more concisely as:

var result = obj?.SomeMethod();

If obj is not null, the SomeMethod() will be invoked on obj, otherwise, the entire expression will evaluate to null. This operator eliminates the need for explicit null checks and makes the code more concise and readable.

It can also be used to access members or elements of a nullable object or nullable value type without causing a null reference exception. For example:

int? length = text?.Length;

If text is not null, Length property will be accessed and assigned to length. If text is null, then length will be assigned null.

The null-conditional operator can also be chained together for multiple null checks. For example:

var result = obj1?.obj2?.SomeMethod();

If either obj1 or obj2 is null, the expression will evaluate to null, otherwise, SomeMethod() will be invoked.

Note that the null-conditional operator is not just limited to method invocations, but it can also be used for property access and array indexing.

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