【DEMO】【C/C++】最简单的一种回调函数

回调函数最简单用法

// CallBackFunc.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//

#include <iostream>
#include <string>
using namespace std;


string toZeroDown(int n, void *contex) {
  cout  << "toZeroDown:" << -*(int*)(contex) << endl;
  return "toZeroDown";
}

string toZeroUp(int n, void *contex) {
  cout << "toZeroUp:" << *(int*)(contex) << endl;
  return "toZeroUp";
}

typedef string(*CallBackFunc)(int n, void *contex);

void registNumCallBack(CallBackFunc callback, void *contex)
{
  int n = 3;
  cout << "The Option of 'callback()' is:" << callback(n, contex) << endl;
}

int main()
{
  for (int i = 0; i < 10; i++)
  {
    if (i % 2) {
      registNumCallBack(toZeroDown, &i);
    }
    else
    {
      registNumCallBack(toZeroUp, &i);
    }
  }
  
}

输出：

toZeroUp:0
The Option of 'callback()' is:toZeroUp
toZeroDown:-1
The Option of 'callback()' is:toZeroDown
toZeroUp:2
The Option of 'callback()' is:toZeroUp
toZeroDown:-3
The Option of 'callback()' is:toZeroDown
toZeroUp:4
The Option of 'callback()' is:toZeroUp
toZeroDown:-5
The Option of 'callback()' is:toZeroDown
toZeroUp:6
The Option of 'callback()' is:toZeroUp
toZeroDown:-7
The Option of 'callback()' is:toZeroDown
toZeroUp:8
The Option of 'callback()' is:toZeroUp
toZeroDown:-9
The Option of 'callback()' is:toZeroDown