C++中C2084错误：‘函数已存在函数体’问题求助

你遇到的C2084错误，核心原因是同一个函数在头文件和源文件中重复定义了函数体。在Employee.h和Manager.h里，你给虚函数displayDetails()写了空函数体{}，这已经算是完成了函数定义；但在对应的.cpp文件里又重新编写了函数实现，直接导致了重复定义冲突。

下面是修正后的代码：

修正后的头文件 #

Employee.h #

#pragma once
#include<string>

class Employee {
public:
    std::string name{};
    int salary{};

    Employee(std::string name, int salary);

    // 仅做函数声明，不写函数体
    virtual void displayDetails();
};

Manager.h #

#pragma once
#include<string>
#include "Employee.h"

class Manager : public Employee {
private:
    std::string department{};

public:
    Manager(std::string name, int salary, std::string department);
    // 仅做声明，不写函数体
    void displayDetails() override;
};

源文件保持不变（已为正确实现） #

Employee.cpp #

#include<iostream>
#include "Employee.h"
#include<string>

Employee::Employee(std::string name, int salary) : name(name), salary(salary) {}

void Employee::displayDetails() {
    std::cout << "Name: " << name << std::endl;
    std::cout << "Salary: " << salary << std::endl;
}

Manager.cpp #

#include<iostream>
#include<string>
#include "Manager.h"

Manager::Manager(std::string name, int salary, std::string department) : 
Employee(name, salary), department(department) {};

void Manager::displayDetails(){
    std::cout << "Name: " << name << std::endl;
    std::cout << "Salary: " << salary << std::endl;
    std::cout << "Department: " << department << std::endl;
}

Main.cpp #

#include "Employee.h"
#include "Manager.h"
#include<string>

int main()
{
    Employee e1("Robert", 5000);
    Employee e2("Sam", 8000);

    e1.displayDetails();
    e2.displayDetails();

    Manager m("Ben", 15000, "Marketing");
    m.displayDetails();

    return 0;
}

补充说明：虚函数的声明与实现分离是C++的常规写法，头文件仅声明函数签名（告诉编译器函数的存在），具体逻辑放在源文件中实现。如果在头文件里写{}，相当于把函数实现放在了头文件中，后续多个源文件包含该头文件时，还可能引发其他重复定义类的错误。

内容的提问来源于stack exchange，提问作者Sampath P