View Full Version : undefined reference to....

January 14th, 2008, 01:28 AM
Hi! i am trying to compile/link a simple application that uses a library called OpenDBX. I have already compiled and installed that library. Now, i am trying to do a simple client of it.

The client (Prueba.c) is just like this:

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <odbx.h>

int main(void) {
puts("Hello World!!");

int err;
odbx_t* handle;

if( ( err = odbx_init( &handle, "mysql", "", "" ) ) < 0 )
fprintf( stderr, "odbx_init(): %s\n", odbx_error( handle, err ) );
return err;


When i try to compile that program (Prueba.c), i has this error:

cc -c -o Prueba.o Prueba.c
gcc -O2 -g -Wall -fmessage-length=0 -L/usr/local/lib -L/usr/local/lib/opendbx -L/usr/local/lib/pkgconfig -o Pruebas Prueba.o
Prueba.o: In function `main':
Prueba.c:(.text+0x3c): undefined reference to `odbx_init'
Prueba.c:(.text+0x57): undefined reference to `odbx_error'
collect2: ld returned 1 exit status
make: *** [Pruebas] Error 1

Those functions (odbx_error and odbx_init are both defined in odbx.h (the header of openDBX y need to include).

I have checked that openDBX libraries are okey. There are in /usr/local/lib , /usr/local/lib/opendbx and /usr/local/lib/pkgconfig.

My makefile is like this:


CCFLAGS = -O2 -g -Wall -fmessage-length=0

OBJS = Prueba.o


TARGET = Pruebas

LDFLAGS = -L/usr/local/lib -L/usr/local/lib/opendbx -L/usr/local/lib/pkgconfig


all: $(TARGET)

rm -f $(OBJS) $(TARGET)

So...can someone please tell what does this error mean ? i think that it doesn't found the library asosiated with de odbx.h, but i am not sure.

Very thanks


January 14th, 2008, 01:38 AM
-I (uppercase i) specifies directories where the compiler will search for #include <???> files (not #include "???") in addition to default locations. eg. -I/path/to/headers/

-L specifies directories where the linker will search for libraries in addition to default locations. eg. -L/path/to/libraries/

-l (lowercase L) tells the linker what libraries it must link your program to in addition to default libraries. eg. -lwhatever will instruct the linker to look for libwhatever.so (in the -L directories) and link that library to your program.

In your case, you are missing at least one -l (lowercase L) flag.