undefined reference to ' header::header() '

[midhun]

header.h :
#ifndef HEADER_H
#define HEADER_H
class header
{
    public:
        header();
};
#endif
 
 
header.cpp : 
#include "header.h"
#include <iostream>
using namespace std;
header::header()
{
    cout<<"i am a banana and why doesn't this work"<<endl;
}
 
 
main.cpp :
#include <iostream>
#include "header.h"
using namespace std;
int main()
{
    header mo;
    return 0;
}

after compiling main.cpp i got the error message:
undefined reference to ' header::header() '
header main are all in same folder

[Banfa]

You didn't just compile main you linked it as well.

Build an application consists of compiling every source file to a object file. Then linking all those object files, along with any require libraries into an application.

You have compiled and linked main.cpp without compiling header.cpp and including it into the link of the application.

Probably the easiest way to solve this is to include header.cpp on the line you used to compile main.cpp

g++ -Wall -pedantic main.cpp header.cpp