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1.前言

本篇目的：C++之普通函数指针和类成员函数指针总结

2.应用实例

#include <iostream>
#include <string>
#include <stdio.h>
#include <functional>
using namespace std;
//一、普通函数回调
//1.返回类型：int; 参数类型(int, int).
int get_data(int x, int y){
  return x+y;
}

//v1.0
int (*callback)(int x, int y);

//v2.0 typedef
typedef int (*TCallBack)(int x, int y);

//v3.0 using
using UCall = int (*)(int x, int y);

//二、类成员函数回调
class ICameraService{
public:
  //1.返回类型：int; 参数类型(int, string buf).
  int test(int a, string buf){
    printf("xxx----------%s(), line = %d, a = %d, buf = %s\n",__FUNCTION__,__LINE__,a,buf.c_str());
    return a;
  }
};

//三、lambda表达式函数回调
int lambda_test(std::function<void(const std::string& desc)> _hidl_cb){
  _hidl_cb("AAAAAAAAAAAAAAAAAAAAAAAA");
  return 12;
}

int main(void){
  //一、普通函数回调
  //v1.0
  callback = get_data;
  printf("line = %d, sum = %d\n", __LINE__,callback(1, 3));

  //v2.0 typedef：定义普通函数指针
  TCallBack tcall;
  tcall = get_data;
  printf("line = %d, sum = %d\n", __LINE__,tcall(10, 30));


  //v3.0 using：定义普通函数指针
  UCall ucall = get_data;
  printf("line = %d, sum = %d\n", __LINE__,ucall(10, 300));

  //v4.0 function + bind:定义普通函数指针
  function<int (int, int)> ft01 = bind(get_data, std::placeholders::_1, std::placeholders::_2);
  printf("line = %d, sum = %d\n", __LINE__,ft01(12, 400));

  //v5.0 atuo + bind:定义普通函数指针
  auto ft02 = bind(get_data, std::placeholders::_1, std::placeholders::_2);
  printf("line = %d, sum = %d\n", __LINE__,ft02(13, 500));
  printf("----------------------------------------------------------------\n\n");
  //二、ICameraService类成员函数回调
  //v1.0 typedef:定义类成员函数指针
  //定义ICameraService类的成员函数的类型TCamCallback,即函数指针的类型为TCamCallback.
  typedef int (ICameraService::*TCamCallback)(int a, string buf);
  TCamCallback tcb;//定义成员函数指针
  //设置回调函数初始化,将成员函数test的地址赋值给函数指针tcb
  tcb = &ICameraService::test;
  ICameraService cam01;//定义ICameraService对象cam01
  (cam01.*tcb)(10, "1111111");
  //或者
  //ICameraService *cam01 = new ICameraService;//定义ICameraService对象cam01
  //(cam01->*tcb)(10, "1111111");

  //v2.0 using:定义类成员函数指针
  using UCamCallback = int (ICameraService::*)(int a, string buf);
  UCamCallback ucb;
  ucb = &ICameraService::test;
  ICameraService cam02;
  (cam02.*ucb)(11, "2222222");

  //v3.0 function + bind:定义类成员函数指针
  ICameraService cam03;
  function<int (int, string)> fb01 = bind(&ICameraService::test, &cam03, std::placeholders::_1, std::placeholders::_2);
  fb01(12, "3333333");

  //v4.0 auto + bind:定义类成员函数指针
  ICameraService cam04;
  auto at01 = bind<int>(&ICameraService::test, &cam04, std::placeholders::_1, std::placeholders::_2);
  at01(13,"4444444");
  printf("----------------------------------------------------------------\n\n");
  //三、lambda表达式函数回调
  //v1.0 直接使用：function + lambda:定义普通函数指针
  int aa  = 10;
  function<int (int, int)> ft03 =[&aa](int a, int b) -> int {
    return a + b + aa;
  };
  printf("line = %d, sum = %d\n", __LINE__,ft03(10,10));

  //v2.0 直接使用：auto + lambda:定义普通函数指针
  int bb  = 100;
  auto ft04 =[&bb](int a, int b) -> int {
    return a + b + bb;
  };
  printf("line = %d, sum = %d\n", __LINE__,ft04(20,20));

  //v3.0 传参的方式:lambda直接回调
  int cc = 1000;
  lambda_test([&cc](string buf)->int{
    printf("line = %d, buf = %s\n", __LINE__,buf.c_str());
    return cc;
  });

  return 0;
}