CODEWITHSUNDEEP
clinux
fSazy
fSazy

Reputation: 336

how to compile and link files in c programming?

I am newbie to c programming language. I have the following files in same directory under centos linux system.

game.h

#ifndef GAME_
#define GAME_

extern void game (void);

#endif

game.c

#include "game.h"

void game (void)
{
   return 23;
}

main.c

#include "game.h"

int main (void)
{
    game();
}

when I compile using the following command..

gcc main.c

I get the error message as below..

/tmp/ccwIlBKt.o: In function main': main.c:(.text+0x7): undefined reference togame' collect2: ld returned 1 exit status

What is the correct way to link my header file?

Upvotes: 3

Views: 4742

Answers (3)

crashh
crashh

Reputation: 93

You should correct your code to this:

game.c

#include "game.h"
int game (void)
{
   return 23;
}

main.c

#include "game.h"
int main (void)
{
    game();
    return 0;
}

Your game.c needs to have the correct return type (int rather than void) and your main method should always return 0 when done to inform that the program ended correctly.

Also I can highly recommend this book when learning C (also good for references for experienced programmers):

C Programming Language, 2nd Edition by Brian W. Kernighan
ISBN-13: 978-0131103627

Upvotes: 0

VINOTH ENERGETIC
VINOTH ENERGETIC

Reputation: 1833

You need to compile and link the two program.

First compile and create object files like this

gcc -c game.c

gcc -c main.c

Then you can generate executable file like this

gcc game.o main.o -o myexe

You can include library files using like this

gcc game.o main.o -o myexe -lsocket -wall

Here the lsocket is the socket library and using -wall displays if any warnings while linking the code

Upvotes: 7

miguel.martin
miguel.martin

Reputation: 1627

gcc game.c main.c

or

gcc *.c

You require to compile the game.c, where the function game() is implemented, that your main function (within main.c) is referring to.

Also you shouldn't be returning a value from a void function. Just leave the body blank, or if you really want a return statement, just type return;. i.e.

void game(void)
{
   return;
}

Otherwise, if you want to return a value, change the declaration of the function to be:

<type-to-return> game(void)
{
    return /* value */;
}

Upvotes: 0

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