What are the usage scenarios of C++ static functions?

Static functions are used in C for class-independent operations or utility functions, including: Utility functions: Provide independent utility functions, such as string manipulation or mathematical operations. Factory method: Creates a new instance of a class and returns a pointer or reference. Constant functions: access constant data and ensure that class state remains unchanged. Enumeration type function: Get the name or description of the enumeration value.

Usage scenarios of C static functions

Static functions are a special type of function in C and do not access classes Non-static member data or functions. They are typically used to handle class-independent operations or provide utility functionality.

Usage scenarios:

1. Utility functions: Provide independent utility functions outside the scope of the class. For example, string operations, mathematical operations, or file I/O.

class Utility {
public:
    static int max(int a, int b) {
        return a > b ? a : b;
    }
};

int main() {
    int result = Utility::max(10, 20);
    std::cout << "Maximum: " << result << std::endl;
    return 0;
}

2. Factory method: Used to create a new instance of a class. Static factory methods do not create an instance of the class, but return a pointer or reference.

class Shape {
public:
    static Shape* createCircle(float radius) {
        return new Circle(radius);
    }
};

int main() {
    Shape* circle = Shape::createCircle(5.0f);
    std::cout << "Area of circle: " << circle->getArea() << std::endl;
    return 0;
}

3. Constant function: Ensure that the class state will not be modified during function execution. Constant functions are typically used to access constant data in a class.

class Person {
public:
    static const char* getGenderString(Gender gender) {
        switch (gender) {
            case Male:
                return "Male";
            case Female:
                return "Female";
        }
        return "Unknown";
    }
};

int main() {
    for (Gender gender : {Male, Female}) {
        std::cout << GenderString(gender) << "; ";
    }
    std::cout << std::endl;
    return 0;
}

4. Enumeration type functions: In operations related to enumeration types, such as getting the name or description of an enumeration value.

enum class Color {
    Red,
    Green,
    Blue
};

class ColorUtil {
public:
    static std::string getColorName(Color color) {
        switch (color) {
            case Color::Red:
                return "Red";
            case Color::Green:
                return "Green";
            case Color::Blue:
                return "Blue";
        }
        return "Unknown";
    }
};

int main() {
    Color color = Color::Green;
    std::cout << "Color name: " << ColorUtil::getColorName(color) << std::endl;
    return 0;
}

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