Attribute lists in C++ function declarations: A customized way to master function behavior

In C, the attribute list in the function declaration allows customization of function behavior, providing fine-grained control over the following aspects: exception handling (noexcept) function type (const/override/final) compiler optimization (nodiscard/maybe_unused)

#C Attribute Lists in Function Declarations: A Guide to Customizing Function Behavior

In C, attribute lists in function declarations allow you to customize functions behavior, providing fine-grained control over compiler optimization, exception handling, and memory management.

Attribute syntax

The attribute list is placed after the right bracket of the function declaration and enclosed in square brackets []. Each attribute consists of a name and a value, separated by commas.

Format:

returnType functionName(parameterList) [attributeList];

Common attributes

Attribute name	Function
noexcept	Declare that the function will not throw an exception
const	Declare the function as a const method
override	Declare the function to override the virtual function in the base class
final	Declaration function cannot be overridden by derived classes
[[nodiscard]]	Warn callers not to ignore function return values
[[maybe_unused]]	Declares that parameters or return values ​​may be unused Use to prevent compiler warnings

Practical case

Example 1: Declare noexcept function

void myFunction() noexcept;  // 声明 myFunction 不抛出异常

Example 2: Overriding virtual functions

virtual void draw() override;  // 声明 draw() 覆盖基类的 draw()

Example 3: Disabling compiler optimization

[[nodiscard]] double calculateArea(double width, double height);  // 警告调用者不要忽略返回值

Notes

• Property list Must immediately follow the closing parenthesis of the function declaration.
• The order of the properties does not matter.
• Some properties are only available for specific types of functions.
• Please read the compiler documentation carefully for the complete list of available properties and limitations.

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