What special uses does C++ function pointer pointer (pointer to function pointer) have?

The function pointer is a pointer to a function pointer in C. It is used to process function pointers and implement functions such as callback functions and dynamic scheduling. Its usage includes: Callback functions: allows functions to be passed as arguments to other functions. Dynamic scheduling: Dynamically call different functions based on incoming data.

Special uses of C function pointer pointers (pointers to function pointers)

Introduction

Function pointer A pointer is a pointer to a function pointer. It provides unique opportunities to write powerful code and create flexible programs.

Implementation of function pointers in C

In C, function pointers can be declared using the ** operator:

typedef void (*FuncPtrPtr)(int);

This declaration creates a pointerFuncPtrPtr that points to a pointer to a function that takes a single integer parameter and returns nothing.

Usage

Common uses of function pointers include:

• Callback functions: Allow functions as parameters passed to other functions.
• Dynamic scheduling: Dynamically call different functions based on the incoming data.
• Achieve polymorphism similar to object-oriented programming.

Practical Case

Let us consider a practical case to show the use of function pointers in callback functions:

#include <iostream>

// 回调函数，打印一个整数
void printInt(int i) {
    std::cout << "整数值：" << i << std::endl;
}

// 使用函数指针指针
void callFuncPtr(FuncPtrPtr func, int val) {
    func(val);
}

int main() {
    // 函数指针，指向 printInt 函数
    void (*funcPtr)(int) = &printInt;

    // 调用 callFuncPtr，将 funcPtr 作为参数
    callFuncPtr(funcPtr, 42);

    return 0;
}

In this example, the callFuncPtr function accepts a pointer to a printInt function pointer. This allows calling the printInt function without knowing its exact address. The output is:

整数值：42

Conclusion

Function pointer Pointer is a powerful tool in C. It provides a flexible and powerful way to deal with function pointers. Make code more reusable and extensible.

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