c++ - 未知函数已存在错误

Question

当我编译我的代码时，我有一个奇怪的错误，它说成员函数已经存在于另一个类中，但错误不是这样说的

Error LNK2005 "public: void __thiscall membershipType::print(void)" (?print@membershipType@@QAEXXZ) already defined in personType.obj Project1 C:\Users\okpal\source\repos\Project1\Project1\Source.obj

还有

Error LNK1169 one or more multiply defined symbols found Project1 C:\Users\okpal\source\repos\Project1\Debug\Project1.exe 1

我想知道是否有人可以帮助找出错误我的类(class)代码在下面

#include <iostream>
#include <string>
using namespace std;
class addressType {  //class defintions and prototypes member variables
public:
    addressType();
    string streetAddressNum, streetName, streetType, city, stateInitials;
    int zipCode;
};
class personType
{
public:
    personType();
    string firstName;
    string lastName;
    int personNum;
    char gender;
    int personID;
    addressType address;
    void setInterest1(string interest1);//mutator
    void setInterest2(string interest2);
    void printPerson();
    string  GetInterest1() const;    // Accessor
    string  GetInterest2() const;
private:
    string SetInterest1;
    string SetInterest2;
};
//define membershipType class
class membershipType :public personType
{
public:
    char membership_type;
    char membership_status;
    membershipType();  // 1st constructor
    membershipType(char, char);  // 2nd constructor
    void print();

};

void membershipType::print() 
{
    cout << GetInterest1();
}

persontype的源代码

#include "personType.h"
personType::personType()
{
    int personNum = 0;
    int personID = 0;
}
addressType::addressType() {
    int zipCode = 0;
}
void personType::setInterest1(string interest1) {
    SetInterest1 = interest1;
}//mutator
void personType::setInterest2(string interest2) {
    SetInterest2 = interest2;
}
string personType::  GetInterest1() const
{
    return SetInterest1;
}// Accessor
string personType:: GetInterest2() const {
    return SetInterest2;
}

void personType :: printPerson() {//constructor

    cout << firstName << " " << lastName << " " << gender << " " <<
        personID << " " << address.streetAddressNum << " "
        << address.streetName << " " << address.streetType
        << " " << address.city << " " << address.stateInitials
        << " " << address.zipCode << " " << SetInterest1 << " " << SetInterest2 << endl;
}

Answer 1

您在第一个代码块中定义了 membershipType::print()，我认为它是从头文件中复制的。在 C++ 中，头文件的内容被插入到包含它们的每个文件中。据推测，您的程序中至少有两个包含此 header 的源文件。当这些源文件被编译成目标文件时，它们都将包含 membershipType::print() 的定义。当您尝试链接它们时，链接器将检测到这两个文件都包含相同符号的定义。它不知道在哪里使用哪个，所以它返回一个错误。

解决此问题的最简单方法是将 membershipType::print() 的定义移动到源文件中。您也可以通过使其内联来修复它。