C++ Compilation problem with G++

nelnel · 07-06-2005, 03:53 AM

hi,
i am writing a simple c++ program to test the linking problem. i know that is it the beginner problem , but i really can't find the solution. i have written total 3 files - main.cpp, abc.cpp and abc.h.
abc.h:

class ABC
{
public:
void test(int i);
};

abc.cpp:

#include "abc.h"

#include <stdio.h>
#include <string.h>

void ABC::test(int i)
{
printf("testing success");
}

main.cpp:

#include <stdio.h>
#include <string>
#include "abc.h"

int main ()
{
ABC tabc;

tabc.test(3);
return 0;
}

I have tried the code in window VC6, there is no problem in exe. and running. But when i compile it under Linux with G++, the error occur in compiling to execute file.

the compilation statement:
g++ -o test.o -c main.cpp
g++ -o test test.o

error message is :

: undefined reference to `ABC::test(int)'
collect2: ld returned 1 exit status

i found that it may be the linking problem, but i can find the solution of that.

Thx for ur help!!

__J · 07-06-2005, 04:22 AM

you are not compiling abc.cpp only main.cpp, so the compiler knows from abc.h that test(int) exist but the linker cannot find it in an object file ( or the system libraries) to link with. try this:

Code:

g++ -c main.cpp
g++ -c abc.cpp
g++ -o test1 abc.o main.o

the reason for the 1 at the end of test is most distro's come with a built in command called "test", so if you current working directory is not part of your path you may inadvertently call it instead of your program.

nelnel · 07-06-2005, 08:30 PM

thx for ur help!!

but i still have the same error in the compilation......

error :

[root@H733-00011 test]# g++ -o test abc.o main.o
strncat.o(.text+0xf3): In function `main':
: undefined reference to `ABC::test(int)'
collect2: ld returned 1 exit status
[root@H733-00011 test]#

what's wrong with it?

Tinkster · 07-06-2005, 08:47 PM

Code:

g++ -c -o abc.o abc.cpp 
g++ -o test abc.o main.cpp

[edit]
Sorry, that's just a shortcut-version of the other statements :)

What your problem is is that the compiler doesn't seem
to see some SYSTEM libraries...
[/edit]

Cheers,
Tink

nelnel · 07-06-2005, 09:39 PM

Really thx for ur kindly help!!!

but i still get the same error....

[root@H733-00011 test]# g++ -o test abc.o main.cpp
/tmp/ccOwk4N6.o(.text+0xf3): In function `main':
: undefined reference to `ABC::test(int)'
collect2: ld returned 1 exit status

Sorry, i haven't clicked the THANKS button~~, ihave clicked it now~~

thxs

vharishankar · 07-06-2005, 09:53 PM

The program compiles and works absolutely fine for me.

Cannot see what your problem could be. Maybe there is a problem with the compiler/linker configuration.

nelnel · 07-06-2005, 09:58 PM

thx for ur help

i have solved the problem because of my typing mistake~~