Detailed explanation of C++ function parameters: best practices in function signature design

Detailed explanation of C function parameters: Best practices in function signature design

In C, function signature defines the name, return type and parameter list. Well-designed function signatures are critical to writing readable, maintainable, and reusable code.

Parameter passing mode

C supports four parameter passing modes:

• Call by value:Copy the value of the parameter into the function.
• Call by reference: Pass the reference of the parameter to the function, and the modified value will be reflected in the caller.
• Call by pointer: Pass the parameter pointer to the function, and the modified value will be reflected in the caller.
• Call by rvalue reference: Allows functions to move or bind to rvalue (rvalue) parameters.

Best Practice

• Prefer using value-passing: For small objects or basic types that do not need to be modified, this It is an efficient and safe delivery method.
• For large or complex objects, use pass-by-reference or pointer: To avoid the overhead of copying, especially for objects that may need to be modified.
• Use const Quote For input parameters: Indicates that the function will not modify the value of the parameter, enhancing code security.
• For output parameters, use a pointer or pass an rvalue reference: Allows the function to modify external variables or move rvalue parameters.
• Limit the number of parameters: Excessive parameters will make the function signature difficult to understand and maintain.
• Use meaningful parameter names: They should clearly indicate the purpose of the parameter.

Practical case

Let us consider a function that calculates the sum of two numbers:

int sum(int a, int b); // 传值

If we want the function to modify the first number, you need to use pass-by-reference:

void add(int &a, int b); // 传引用

If we know that the first parameter will not be modified inside the function, we can use const reference to improve security:

int sum(const int &a, int b); // 传 const 引用

Note :

• Passing pointers and passing references are very similar in syntax, but different in semantics.
• Passing rvalue references only works in C 11 and later.
• The correct use of parameter passing mode can greatly improve code efficiency and security.

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