C++ function types and characteristics

C functions have the following types: simple functions, const functions, static functions, and virtual functions; features include: inline functions, default parameters, reference returns, and overloaded functions. For example, the calculateArea function uses π to calculate the area of a circle of a given radius and returns it as output.

#Types and Properties of C Functions

A function in C is a reusable block of code that receives input and produces output. Functions have an explicit name, parameter list, and return value type.

Function type

Simple function:The simplest function type without any prefix or suffix modifiers.

void myFunction(); // 返回 void，不接收参数

const Function:The function does not modify the data it accesses.

const int &myFunction(const int &x); // 返回常引用，接收常引用

Static function:The function does not depend on the class object and can only access static data members.

static void myFunction(); // 静态函数，不接收参数

Virtual function:Function used for polymorphism, allowing derived classes and parent classes to have functions with the same name, but different behaviors.

virtual void myFunction() = 0; // 纯虚函数，必须在派生类中重写

Function features

Inline function:Inline the function code directly into the calling function to improve performance.

inline int myFunction(int x) { return x * x; } // 内联函数，接收一个整型参数，返回平方的值

Default parameters:Allow function parameters to specify default values when called.

int myFunction(int x, int y = 10); // 默认参数为 10

Reference return:The function can return a reference to the data, allowing the caller to directly modify the original data.

int &myFunction(int &x); // 返回对整型变量的引用

Overloaded functions:Functions with the same name but different parameter lists.

int myFunction(int x); // 一个参数 double myFunction(double x); // 一个 double 参数

Practical case

Consider a function that calculates the area of a circle:

#include  double calculateArea(double radius) { return M_PI * radius * radius; // 返回圆的面积 } int main() { double radius = 5.0; double area = calculateArea(radius); cout << "半径为 " << radius << " 的圆的面积为 " << area << endl; return 0; }

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