Object oriented: "Undefined Reference to" in main.cpp

Question

I’m starting POO (Object Oriented Programming) and am separating my attributes and methods from the class into different files.

They are reading each but in main.cpp is giving the error "Undefined Reference to.. "

The strange thing is that when I start typing to use some method, it appears for me to choose as shortcut

I’m using the VS Code;

ps: I’m using tag as int for testing, to see if it runs; If I write normal code everything in a file works normal. .

main.cpp:

#include <iostream>
#include <string.h>
#include <stdlib.h>

#include "Carro.h"

using namespace std;

int main(){

    Carro c1;
    c1.setMarca(3);
    c1.setAno(2018);

    Carro c2;
    c2.setMarca(4);
    c2.setAno(2020);

    cout << c1.getAno() ;


    return 0;
}

Car.cpp:

#include <stdlib.h>

#include "Carro.h"


// Marca do carro:
int Carro::setMarca (int marca) { 
    this->marca = marca; 
}

int Carro::getMarca () {
    return marca;  
}


// Ano do carro:
int Carro::setAno (int ano) { 
    this-> ano = ano; 
}

int Carro::getAno () { 
    return ano; 
}

Car. h:

#ifndef CARRO_H
#define CARRO_H

#include <stdlib.h>


class Carro {    
    private:
        int ano, marca;

    public:
        int setMarca(int marca);
        int getMarca();

        int setAno(int ano);
        int getAno();    
};

#endif // CARRO_H

.

error:

.

recognizing in vs code the attributes in main:

Answer 1

Good.. I managed to solve in two methods:

- Primeiro (errado):

Just take the #include "Carro.h" of the file . cpp and put at the end of the file . h #include "Carro.cpp"

But this is not recommended.

The #include basically pulls what’s written in that file/library and puts it in place. When we include the definitions of our attributes below the created attributes two things happen:

• Loses the essence of creating another file. you can do this in one file, without having to separate in others;

• In larger projects you may have conflicts; When you put the arquivo.h (ou .hpp) at the beginning of arquivo.cpp vc is placing its defined attributes of the class on top of the code, so that below you can define each attribute. And that you can do again on arquivo2.cpp, define the attributes and dps configure them again without interference.

.

- Segundo (certo)

Just put the #include "Carro.h" at the beginning of arquivo.cpp and when compiling should have compiled the two files: main.cpp and arquivo.cpp.

.

.

In this video (insert link description here) shows how to debug a program in C/C++ simply by pressing F5 in VS Code, I used it to configure my compilation.

To compile two files, just add one more file in the task.json:

// Meu task.json
{
    "version": "2.0.0",
    "tasks": [
        {
            "label": "echo",
            "type": "shell",
            "command": "g++",
            "args": [
                "-g",
                "main.cpp", 
                "-g",
                "Vetor.cpp",
            ],
            "group": {
                "kind": "build",
                "isDefault": true
            }
        },
        {
            "type": "shell",
            "label": "g++.exe build active file",
            "command": "C:\\MinGW\\bin\\g++.exe",
            "args": [
                "-g",
                "${file}",
                "-o",
                "${fileDirname}\\${fileBasenameNoExtension}.exe"
            ],
            "options": {
                "cwd": "C:\\MinGW\\bin"
            }
        }
    ]
}

Note that in my arguments ("args") I put two files, so it runs normally :)

PS: Every time you go to debug (press F5) you need to place the location of the file(s) in the "args" (the program will run in an external (terminal) window). If you just want to run the program you need to download an extension ("C/C++ Compile Run") and press F6 (the program will run on the VS Code terminal itself)

WARNING: The extension only runs a single file. To use VS Code to compile you need the task.json where vc tells which files should be compiled.

If you don’t want all this work, just download an IDE that it already does all this for you.