一、头文件

头文件中写类的声明、结构的声明、函数原型、宏定义等
注意不可以定义全局变量，否则可能会引起重复定义的错误

• testStruct.h

      #pragma once
      #define MAXPRICE 200000
  
      //结构体定义，这个地方一定要加typedef(否则vs2019会报重复定义的错)
      typedef struct Book {
          char Name[50];
          int ID;
          double price;
      }book;
  
      //车辆类定义
      class Vehicle {
      public:
          char Brand[50];
          double price;
          int siteNum;
          Vehicle(void) {
              price = 0;
              siteNum = 0;
              strcpy_s(Brand, "car");
          }
          Vehicle(char* id, double newprice, int sitenum) {
              strcpy_s(Brand, id);//char*转char[]拷贝  char[]转char*直接赋值
              price = newprice;
              siteNum = sitenum;
          }
      public:
          void printVehicleInfo();
      };
  
      //结构体作为参数
      void printDetail(Book book);
  
      //结构体指针作为参数
      void printDetail(Book* book);
  
      //对象指针作为参数
      void printCarInfo(Vehicle* vehicle);
  
      //对象引用作为参数
      void printCarInfo(Vehicle& vehicle);
  
      //复制信息，对象引用作为参数，返回引用
      Vehicle* copyCarInfo(Vehicle& vehicle);
  

二、源文件

源文件中主要是对.h文件中声明的定义、实现，注意引入“testStruct.h”

• testStruct.cpp

      #include <iostream>
      #include <string>
      #include "testStruct.h"
      using namespace std;
  
  
      //输出详细信息
      void printDetail(Book book) {
          cout << "书名:" << book.Name << endl;
          cout << "ID:" << book.ID << endl;
          cout << "价格:" << book.price << endl;
      }
  
      void printDetail(Book* book) {
          cout << endl;
          cout << "指针作为参数:" << endl;
          cout << "书名:" << book->Name << endl;
          cout << "ID:" << book->ID << endl;
          cout << "价格:" << book->price << endl;
      }
  
      void Vehicle::printVehicleInfo() {//this是个指针
          cout << "品牌:" << this->Brand << endl;
          cout << "价格:" << this->price << endl;
          cout << "承载人数:" << this->siteNum << endl;
      }
  
      void printCarInfo(Vehicle* vehicle) {
          cout << "品牌:" << vehicle->Brand << endl;
          cout << "价格:" << vehicle->price << endl;
          cout << "承载人数:" << vehicle->siteNum << endl;
      }
  
      void printCarInfo(Vehicle& vehicle) {
          cout << "品牌:" << vehicle.Brand << endl;
          cout << "价格:" << vehicle.price << endl;
          cout << "承载人数:" << vehicle.siteNum << endl;
      }
  
      Vehicle* copyCarInfo(Vehicle& vehicle) {
          Vehicle* pnewvehicle = &vehicle;
          strcpy_s(vehicle.Brand, "MINI-point");
          vehicle.price = 200000;
          return pnewvehicle;
      }
  

三、不同文件之间的调用

在其他文件(例如含有main()入口的testNew.cpp)中使用testStruct定义的函数，只需要引入testStruct.h即可

• testNew.cpp

      #include <iostream>
      #include <string>
      #include "testStruct.h"
      using namespace std;
  
      int main(){
          
          Vehicle myminicar;
          Vehicle* minicarinfo = copyCarInfo(myminicar);
          printCarInfo(minicarinfo);
          cout << "------------分割线------------" << endl;
          cout << "设置的宏定义MAXPRICE:" <<MAXPRICE << endl;
      }
  

• 执行结果
  

四、问题记录

在cpp文件中结构体可以不使用typedef，可以直接定义，但是在头文件中不加typedef会出现报错