Question Mark syntax on method call in C#

Question Mark syntax on method call in C#

The question mark syntax on a method call in C# is called the null-conditional operator, and it was introduced in C# 6.0.

It allows you to safely access properties and methods of an object that may be null, without causing a null reference exception. The syntax is ?., and you place it before the property or method you want to access.

Here's an example:

string name = person?.Name;

In this example, the ?. operator is used to safely access the Name property of the person object. If person is null, the expression will return null instead of throwing a null reference exception.

You can also use the null-conditional operator with method calls. Here's an example:

int? length = person?.GetName()?.Length;

In this example, the ?. operator is used to safely call the GetName method on the person object. If person is null, the entire expression will return null instead of throwing a null reference exception. If GetName returns null, the Length property will not be called, and the entire expression will return null.

The null-conditional operator is a useful feature in C# that helps you write more concise and robust code. However, it should be used with care, as it can make your code more difficult to read and understand if overused.

Examples

  1. "C# code with question mark syntax on method call - What does it mean?"

    • Description: Explore the null-conditional operator (?.) to safely invoke a method on a potentially null object.
    • Code:
      string result = person?.GetName();

  2. "C# code with question mark syntax and method with parameters - What does it mean?"

    • Description: Learn how to use the null-conditional operator with a method that takes parameters.
    • Code:
      string result = person?.GetName("Mr.");

  3. "C# code with question mark syntax and method chaining - What does it mean?"

    • Description: Understand how to chain multiple method calls using the null-conditional operator.
    • Code:
      int? length = person?.GetName()?.Length;

  4. "C# code with question mark syntax on static method call - What does it mean?"

    • Description: Explore using the null-conditional operator with a static method call.
    • Code:
      string result = Person?.GetDefaultName();

  5. "C# code with question mark syntax on method call with return value - What does it mean?"

    • Description: Learn how to use the null-conditional operator with a method that returns a value.
    • Code:
      int? age = person?.GetAge() ?? 0;

  6. "C# code with question mark syntax on method call and null coalescing - What does it mean?"

    • Description: Understand combining the null-conditional operator with the null coalescing operator.
    • Code:
      string name = person?.GetName() ?? "DefaultName";

  7. "C# code with question mark syntax on method call and conditional logic - What does it mean?"

    • Description: Explore using the null-conditional operator in conditional logic with method calls.
    • Code:
      bool isValid = person?.IsDataValid() == true;

  8. "C# code with question mark syntax on method call and event invocation - What does it mean?"

    • Description: Learn how to use the null-conditional operator when invoking a method that raises an event.
    • Code:
      person?.OnDataUpdated?.Invoke(this, EventArgs.Empty);

  9. "C# code with question mark syntax on method call and LINQ query - What does it mean?"

    • Description: Understand using the null-conditional operator in LINQ queries with method calls.
    • Code:
      var validPersons = persons?.Where(p => p.IsValid()).ToList();

  10. "C# code with question mark syntax on method call and custom extension method - What does it mean?"

    • Description: Explore using the null-conditional operator with a custom extension method.
    • Code:
      var result = person?.CustomExtensionMethod()?.ProcessData();

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