What is the role of C++ function pointers?

A function pointer is a variable pointing to a function, allowing functions to be called dynamically without knowing the actual function at compile time. Functions include: dynamic function calls, callback functions, event processing and strategy patterns. Practical cases include: dynamic function calling (calling a specific function through a function pointer), callback function (passing a function as a callback parameter to other functions), and event processing (calling a specific function when a specific event occurs).

#C The wonderful use of function pointers

Introduction to function pointers

A function pointer is a variable that points to a function. It stores a pointer to the function's memory address. This mechanism allows us to call functions dynamically without knowing the actual function at compile time.

Function

The function pointer has the following functions:

• Dynamic function call: Allows the decision on which function to call at runtime.
• Callback function: Supports passing functions as parameters to other functions.
• Event handling: Allows calling specific functions when specific events occur.
• Strategy pattern: Provides a way to select an algorithm or behavior at runtime.

Practical case

Dynamic function call

// 定义函数：
void Print(int num) {
  cout << "数字：" << num << endl;
}

// 定义函数指针：
using PrintFunc = void (*)(int);

int main() {
  // 指向 Print 函数的函数指针：
  PrintFunc printPtr = Print;

  // 通过函数指针调用函数：
  printPtr(10);  // 输出："数字：10"

  return 0;
}

Callback function

// 定义一个接收回调函数的函数：
void CallMeBack(int (*callback)(int)) {
  if (callback) {
    callback(10);
  }
}

// 定义回调函数：
int Callback(int num) {
  cout << "Callback 接收的数字：" << num << endl;
  return 0;
}

int main() {
  // 将 Callback 函数作为回调参数传递：
  CallMeBack(Callback);

  return 0;
}

Event handling

// 定义一个事件处理函数：
void OnClick() {
  cout << "单击发生！" << endl;
}

// 定义事件处理函数指针：
using EventFunc = void (*)();

int main() {
  // 指向 OnClick 函数的事件处理函数指针：
  EventFunc eventHandler = OnClick;

  // 模拟鼠标单击事件：
  eventHandler();  // 输出："单击发生！"

  return 0;
}

The above is the detailed content of What is the role of C++ function pointers?. For more information, please follow other related articles on the PHP Chinese website!