Multpile definition error of a header declared variable when there's just one definition/declaration

Question

I have a header file where I've defined a structure and its variable 'editor' and am using it in multiple files. I have not declared it anywhere else, yet it gives me multiple declaration error. I've also tried using #ifndef but to no avail.

This is my header file:

editorlib.h

#ifndef ED_LIB
#define ED_LIB

//#include files

struct terminalProperties {
    int rows,cols;
    struct termios origTerm;
    int mode;
}editor;
int TERMINATE=0;

//function definitions

#endif

My editorlib.cpp

#ifndef EDITORLIBRARY_H
#define EDITORLIBRARY_H
#include "editorLibrary.h"

getAttr() {
    tcgetattr(STDIN_FILENO, TCSAFLUSH, &editor.origterm);
}
//further code
#endif

Driver file vi_editor.cpp:

#ifndef MAIN_H
#define MAIN_H

#include "editorLibrary.h"
int main(){

    //some code

    while(1){
        //some code
        if(TERMINATE)
            break;
    }
    //some code
    return 0;
}

#endif

My normal.cpp:

#ifndef NORMALMODE_H
#define NORMALMODE_H
#include "editorLibrary.h"

void normalMode() {
    editor.mode = 1;
    //further code
}
#endif

My command.cpp:

#ifndef COMMANDMODE_H
#define COMMANDMODE_H
#include "editorLibrary.h"

void commandMode() {
    editor.mode = 2;
    //further code
}
#endif

Similarly I have a few other files where I'm not declaring the editor variable but just using it in a similar manner as above. I can't seem to find why it tell me about multiple declaration.

So don't do that. There is a One Definition Rule. Observe it. — user207421, Aug 23 '17 at 10:47
remove the variable definition from header. use an `extern` declaration and define the variable in one of the source files. That's it. — Sourav Ghosh, Aug 23 '17 at 10:48
I had tried using extern and declaring the variables in my driver program source code which did not work as well. Later now I declared them in my editorlib.cpp which somehow worked. — telekineser, Aug 23 '17 at 11:04

score 0 · Accepted Answer · answered Aug 23 '17 at 10:58

0

Multpile definition of a header declared variable

This is already a violation of the One Definition Rule. The simple answer is "don't". You can only declare in a header, via extern, and define in a single .cpp file.

answered Aug 23 '17 at 10:58

user207421

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This worked when I declared them in editorlib.cpp file but not when I declared them in my driver code of vi_editor.cpp file – telekineser Aug 23 '17 at 11:06
Not knowing what you did it is impossible to comment, but the One Definition Rule applies. – user207421 Aug 23 '17 at 11:11

Multpile definition error of a header declared variable when there's just one definition/declaration

1 Answers1