Thread: Function calling problem

Hey guys,
Im new to c and im having trouble calling a function from a file "that.c" and im making the call from a file "this.c" and they both have "common.h" in common

i dont know what im doing wrong

that.c

Code:

#import "common.h"
#import <stdio.h>

void sayHello(){
    printf("hello");
}

this.c

Code:

#import "common.h"
#import <stdio.h>

int main(void){
    sayHello();
}

and finally
common.h

Code:

#ifndef HEADER_FILE
#define HEADER_FILE

// prototype
void sayHello();


#endif;

and the error im getting is

Code:

$gcc this.c 
/tmp/ccWzgg44.o: In function `main':
this.c:(.text+0x12): undefined reference to `sayHello'
collect2: ld returned 1 exit status

please help

Move the prototype from the header to that.c and create another in this.c with an extern.

Code:

extern void sayHello();

Replace #import by #include

As has been danced around, your "gcc this.c" is wholly inadequate for compiling that.c, since that.c is not mentioned anywhere. Your command line needs to have all the necessary .c files on it.

Originally Posted by tabstop

As has been danced around, your "gcc this.c" is wholly inadequate for compiling that.c, since that.c is not mentioned anywhere. Your command line needs to have all the necessary .c files on it.

or .o files. You could compile these one at a time using -c for each, then at the end link the .o files together.