What is the Role of the \'default\' Keyword in C Class Function Declarations?

Implicit Function Implementation in Classes: Unveiling the Role of "default"

When working with class function declarations, the keyword "default" can be encountered alongside them. Understanding its significance is crucial for effective C programming.

What Purpose Does "default" Serve?

In C 11 and later versions, the "default" keyword plays a vital role in function declarations:

1. Compiler-Generated Function Implementation:
   Using "default" instructs the compiler to generate the function implementation automatically. This eliminates the need to specify an explicit function body.
2. Default Constructors and Assignment Operators:
   When applied to constructors and assignment operators, "default" creates compiler-generated versions of these functions that perform the default behavior (e.g., constructing an object with default values, copying an object).

In the example provided:

<code class="cpp">class C {
  C(const C&) = default;
  C(C&&) = default;
  C& operator=(const C&) & = default;
  C& operator=(C&&) & = default;
  virtual ~C() { }
};</code>

• The copy constructor and copy assignment operator are compiler-generated.
• The move constructor and move assignment operator are also compiler-generated.
• The destructor is not declared as "default" since its implementation is explicitly provided.

Benefits of Using "default"

Employing "default" offers several advantages:

• Reduced Boilerplate Code: Eliminates the need to write repetitive, boilerplate function bodies.
• Clarity and Consistency: Ensures uniform and concise function declarations.
• Adherence to Rules: Simplifies compliance with the complex rules governing compiler-generated functions.

The above is the detailed content of What is the Role of the \'default\' Keyword in C Class Function Declarations?. For more information, please follow other related articles on the PHP Chinese website!