undefined reference

[wizumwalt]

Hi,

This is a small test case I wrote in which I can't understand why I have an undefined reference. I have an undefined reference which I thought only requires linking w/ the libs that contain this symbol, which I am. The function dm_connect() is in the library libdm, and this is on the g++ command line when I compile as shown. The libdm is a C library and I'm calling this in my C++ program.

Can anyone help me understand what I'm doing wrong?

--- Compile and Error

$ g++ $(pkg-config --cflags glib-2.0) -I/usr/include -I/usr/local/include -I/home/joe/Projects/net-1.0/util -L/usr/local/lib -L/home/joe/Projects/net-1.0/libdm $(pkg-config --libs glib-2.0) -ldm main.cpp
/tmp/ccksTRGA.o: In function `main':
main.cpp.text+0x30): undefined reference to `dm_connect(char*, unsigned short)'
collect2: ld returned 1 exit status

--- Source
#include <stdio.h>

#include "gxclient.h"

using namespace std;

int main ()
{
int fd = -1;

uint16_t port = 11002;

char *dmhostname = "localhost";

fd = dm_connect(dmhostname, port);

if (fd < 0) {
printf("failed\n");
}

return 0;
}

[moses7]

You may need the developer libraries and not the standard ones. Try obtaining libdm-dev in addition to libdm, which will probably be needed for developer builds.

[Rubberman]

Also, since this is a C-linkage function used in a C++ program, you need to make sure that you have declared the function as extern "C" either directly, or enclosing it and other C declarations inside a

#ifdef __cplusplus
extern "C" {
#endif
.
.
.
#ifdef __cplusplus
}
#endif

block.