"undefined reference to ..." Error

[wtbrannan]

Hello,

I have seen the other posts and I know it's sort of been addressed but I believe I have everything in order but can't seem to get past this error. 

Here is what I have
Using code::blocks with GNU gcc Compiler

I have a header file (vacapi.h) and a library(libvac.a) provided by an SDK. 

I have included the following in my Linker settings

pthread
X11
Xv
Xext
../Path/To/lib/libvac.a

I have also included the following in my Search Directories

../usr/include/X11
../Tools/SDKFolder/include [THIS IS WHERE the vacapi.h file is located]
../Tools/SDKFolder/lib [THIS IS WHERE the libvac.a file is located]

When I attempt to make a build I get the following.


-------------- Build: Debug in MyProject ---------------

g++ -Wall -fexceptions  -Wall -g    -I../../../../usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib -I../../../../usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib  -c /home/billbrannan/Dev/MyProject/PktParser.cpp -o obj/Debug/PktParser.o
g++ -Wall -fexceptions  -Wall -g    -I../../../../usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib -I../../../../usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib  -c /home/billbrannan/Dev/MyProject/OverlayEng.cpp -o obj/Debug/OverlayEng.o
g++ -Wall -fexceptions  -Wall -g    -I../../../../usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib -I../../../../usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib  -c /home/billbrannan/Dev/MyProject/main.cpp -o obj/Debug/main.o
g++ -Wall -fexceptions  -Wall -g    -I../../../../usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib -I../../../../usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib  -c /home/billbrannan/Dev/Common/Markup.cpp -o obj/Debug/Common/Markup.o
g++ -Wall -fexceptions  -Wall -g    -I../../../../usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib -I../../../../usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib  -c /home/billbrannan/Dev/Common/c_serial_port.cc -o obj/Debug/Common/c_serial_port.o
g++  -o bin/Debug/MyProject obj/Debug/PktParser.o obj/Debug/OverlayEng.o obj/Debug/main.o obj/Debug/Common/Markup.o obj/Debug/Common/c_serial_port.o    -lpthread -lX11 -lXv -lXext ../Tools/SDKFolder/lib/libvac.a -lpthread -lX11 -lXv -lXext ../Tools/SDKFolder/lib/libvac.a
obj/Debug/OverlayEng.o: In function `OverlayEng::Init()':
/home/billbrannan/Dev/MyProject/OverlayEng.cpp:102: undefined reference to `InitVAC(unsigned long, _XDisplay*)'
collect2: ld returned 1 exit status
Process terminated with status 1 (0 minutes, 2 seconds)
1 errors, 0 warnings

Any help is greatly appreciated,
Thanks,
Bill

[stahta01]

../Tools/SDKFolder/lib/libvac.a

Add the library "vac" to library list
Add the path "../Tools/SDKFolder/lib/" to search linker list.

rebuild project.

Tim S.

[wtbrannan]

Tim,

Thank you very much but I am still getting the same error.

To be sure I did the right steps here is what I did.

I changed "../Tools/SDKFolder/lib/libvac.a" to "vac" in my Linker Settings (Under all 3 Scopes - Project - Debug - Release)
I added "../Tools/SDKFolder/lib" to Search Directories -> Linker Tab (Under all 3 Scopes - Project - Debug - Release)

Build-> Clean (just to be certain)
Build-> Rebuild

Thanks,
Bill

[stahta01]

I don't see a build log.

Note to all beginners: The order the libraries are in makes a difference to whether it will link right.
In MinGW GCC try moving the Libraries with the link errors to the top of the "Link Libraries" list.

Note: Adding the same libraries many times makes it harder to understand the build log.
Add all the Libraries ONLY to the project Scope/Target till your learn the right way to do the adding.

Tim S.

[wtbrannan]

Thanks. 

I changed the scopes and will now start manipulating Link orders.

Here is the last build log.

Thanks again Tim. You've been very helpful.


-------------- Build: Debug in MyProject ---------------

g++ -Wall -g    -I/usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib  -c /home/billbrannan/Dev/MyProject/PktParser.cpp -o obj/Debug/PktParser.o
g++ -Wall -g    -I/usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib  -c /home/billbrannan/Dev/MyProject/OverlayEng.cpp -o obj/Debug/OverlayEng.o
g++ -Wall -g    -I/usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib  -c /home/billbrannan/Dev/MyProject/main.cpp -o obj/Debug/main.o
g++ -Wall -g    -I/usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib  -c /home/billbrannan/Dev/Common/Markup.cpp -o obj/Debug/Common/Markup.o
g++ -Wall -g    -I/usr/include/X11 -I../Tools/SDKFolder/include -I../Tools/SDKFolder/lib  -c /home/billbrannan/Dev/Common/c_serial_port.cc -o obj/Debug/Common/c_serial_port.o
g++ -L../Tools/SDKFolder/lib -L/usr/lib  -o bin/Debug/MyProject obj/Debug/PktParser.o obj/Debug/OverlayEng.o obj/Debug/main.o obj/Debug/Common/Markup.o obj/Debug/Common/c_serial_port.o    -lpthread -lX11 -lXv -lXext -lvac
obj/Debug/OverlayEng.o: In function `OverlayEng::Init()':
/home/billbrannan/Dev/MyProject/OverlayEng.cpp:102: undefined reference to `InitVAC(unsigned long, _XDisplay*)'
collect2: ld returned 1 exit status
Process terminated with status 1 (0 minutes, 2 seconds)
1 errors, 0 warnings

[wtbrannan]

Hello Tim,

I believe I found it. The solution seems so simple but just one of those "beginner" omissions. 

Note for everyone else:

If your program is written in C++ and the lib is in C, then you must wrap the #include statement with extern "C" {[include.h file]}

Thanks for your help once again.
Bill