Visual Studio Code找不到我在C ++中声明和定义的类

Question

I'm getting a linker error when I separate my class declarations and function definitions into their own files. The code gets through the compiler when all the code is in one singular .cpp file, but that's not what I'm trying to accomplish. I want to know how I can separate my code into different files.

Here is all the code. This code runs completely fine.

// main.cpp

#include <string>

#ifndef ANIMAL_H
#define ANIMAL_H

class Animal {
private:
    std::string name;
    int height;
    int weight;
    std::string color;

public:
    Animal(std::string, int, int);
};

#endif

Animal::Animal(std::string name, int height, int weight) {
    this -> name = name;
    this -> height = height;
    this -> weight = weight;
}

int main() {
    Animal dog("Spotty", 20, 50);

    return 0;
}

Although, since I want to separate the code, I put the class declaration into it's own file and the function definitions into their own file, and I get this.

// main.cpp

#include <string>
#include "Animal.hpp"

int main() {
    Animal dog("Spotty", 20, 50);

    return 0;
}



// Animal.hpp

#include <string>

#ifndef ANIMAL_H
#define ANIMAL_H

class Animal {
private:
    std::string name;
    int height;
    int weight;
    std::string color;

public:
    Animal(std::string, int, int);
};

#endif



// Animal.cpp

#include "Animal.hpp"

Animal::Animal(std::string name, int height, int weight) {
    this -> name = name;
    this -> height = height;
    this -> weight = weight;
}

This is the error I get when I compile the second version of main.cpp.

main.obj : error LNK2019: unresolved external symbol " public: __thiscall Animal::Animal(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,int,int) " (??0Animal@@QAE@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@HH@Z) referenced in function _main

main.exe : fatal error LNK1120: 1 unresolved externals

Answer 1

Try giving the parameters in your constructor names. eg

Animal(std::string name, int h, int w);

The constructor doesnt do anything right now. Do you have the function in another file?