[FIXED] Why am I getting an error on the makefile.win? (dev c++ 6.3)

Issue

I am using C++, I'm quite new to programming and wanted to try out some things.

I have been smooth sailing until I reached multifile programming..

I tried putting all the contents of the 3 files into a single cpp file and it works:

#include <iostream>

using namespace std;

const int numOf_people = 4;

struct person
{
    std::string name;
} individual[4]; // 4 identities

void input_movieName (person individual[], int numOf_people)
{
    for (int i = 0; i < numOf_people; i++)
    {
        cout << "Enter individual " << i+1 << " name : ";
        cin >> individual[i].name;
    }
}

int main()
{
    input_movieName (individual, numOf_people);
    
    for (int i = 0; i < numOf_people; i++)
    {
        cout << "Name of person " << i+1 << " : " << individual[i].name << endl;
    }
}

but these would just not work:

head.h

#ifndef MAIN
#define MAIN

const int numOf_people = 4;

struct person
{
    std::string name;
} individual[4]; // 4 identities

void input_movieName (person*, int);

#endif

main.cpp

#include <iostream>
#include "head.h"

using namespace std;

int main()
{
    input_movieName (individual, numOf_people);
    
    for (int i = 0; i < numOf_people; i++)
    {
        cout << "Name of person " << i+1 << " : " << individual[i].name << endl;
    }
}

func.cpp

#include <iostream>
#include "head.h"

using namespace std;

void input_movieName (person individual[], int numOf_people)
{
    for (int i = 0; i < numOf_people; i++)
    {
        cout << "Enter individual " << i+1 << " name : ";
        cin >> individual[i].name;
    }
}

I keep getting an error in the makefile.win pointing this error out:

$(BIN): $(OBJ)
    $(CPP) $(LINKOBJ) -o $(BIN) $(LIBS)

the error says

"head.h:9: multiple definition of `individual'; head.h:9: first defined here" >I removed the directories but I think you guys get the point

Solution

The error is that you define the variable individual in the header file:

struct person
{
    std::string name;
} individual[4];

That means the variable will defined in each translation unit where the header file was included, and C++ only allows variables (and functions) to be defined once.

I suggest you split these into the separate structure definition, and a separate variable declaration:

struct person
{
    std::string name;
};

extern struct individual[4];

Then in a single source file you define the variable:

struct individual[4];

Answered By - Some programmer dude

Answer Checked By - Marilyn (PHPFixing Volunteer)