trouble linking with g++

WanglessOlasov · 12-27-2003, 06:04 PM

Hi, i'm trying to start on my science fair project, in which i'll be programming... a LOT. I've done a little c++ before, but never on linux, and i'm having some trouble compiling some sample code. I'm using the c++ libraries for player/stage, all of which can be found on playerstage.sourceforge.net. I installed player and stage, as well as all the libraries for c++. What i believe are the library files (like i said, i'm not too familiar with this stuff... they're binary files that end in ".a" so i'm assuming that they're libraries) are in /usr/local/lib/, and the header files are in /usr/local/include/. They gave me some sample code called forage.cc, but when i try to compile it with g++ -o forage forage.cc, it doesn't compile and i get this output (i don't know how much is really needed, so i'll post it all):

Code:

~g++ -o forage forage.cc                                                                                                     
/tmp/cc0PnmXM.o(.text+0x212): In function `main':
: undefined reference to `PlayerClient::PlayerClient[in-charge](char const*, int)'
/tmp/cc0PnmXM.o(.text+0x260): In function `main':
: undefined reference to `BlobfinderProxy::BlobfinderProxy[in-charge](PlayerClient*, unsigned short, unsigned char)'
/tmp/cc0PnmXM.o(.text+0x2d0): In function `main':
: undefined reference to `PlayerClient::Read()'
/tmp/cc0PnmXM.o(.text+0x2f0): In function `main':
: undefined reference to `PositionProxy::Print()'
/tmp/cc0PnmXM.o(.text+0x30f): In function `main':
: undefined reference to `GripperProxy::SetGrip(unsigned char, unsigned char)'
/tmp/cc0PnmXM.o(.text+0x4bf): In function `main':
: undefined reference to `GripperProxy::SetGrip(unsigned char, unsigned char)'
/tmp/cc0PnmXM.o(.text+0x74e): In function `main':
: undefined reference to `GripperProxy::SetGrip(unsigned char, unsigned char)'
/tmp/cc0PnmXM.o(.text+0x766): In function `main':
: undefined reference to `GripperProxy::SetGrip(unsigned char, unsigned char)'
/tmp/cc0PnmXM.o(.text+0x838): In function `main':
: undefined reference to `BlobfinderProxy::~BlobfinderProxy [in-charge]()'
/tmp/cc0PnmXM.o(.text+0x8aa): In function `main':
: undefined reference to `PlayerClient::~PlayerClient [in-charge]()'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN8GpsProxyD1Ev+0xb): In function `GpsProxy::~GpsProxy [in-charge]()':
: undefined reference to `vtable for GpsProxy'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN8GpsProxyD1Ev+0x16): In function `GpsProxy::~GpsProxy [in-charge]()':
: undefined reference to `ClientProxy::~ClientProxy [not-in-charge]()'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN8GpsProxyC1EP12PlayerClientth+0x32): In function `GpsProxy::GpsProxy[in-charge](PlayerClient*, unsigned short, unsigned char)':
: undefined reference to `ClientProxy::ClientProxy[not-in-charge](PlayerClient*, unsigned short, unsigned short, unsigned char)'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN8GpsProxyC1EP12PlayerClientth+0x3e): In function `GpsProxy::GpsProxy[in-charge](PlayerClient*, unsigned short, unsigned char)':
: undefined reference to `vtable for GpsProxy'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN12GripperProxyD1Ev+0xb): In function `GripperProxy::~GripperProxy [in-charge]()':
: undefined reference to `vtable for GripperProxy'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN12GripperProxyD1Ev+0x16): In function `GripperProxy::~GripperProxy [in-charge]()':
: undefined reference to `ClientProxy::~ClientProxy [not-in-charge]()'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN12GripperProxyC1EP12PlayerClientth+0x32): In function `GripperProxy::GripperProxy[in-charge](PlayerClient*, unsigned short, unsigned char)':
: undefined reference to `ClientProxy::ClientProxy[not-in-charge](PlayerClient*, unsigned short, unsigned short, unsigned char)'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN12GripperProxyC1EP12PlayerClientth+0x3e): In function `GripperProxy::GripperProxy[in-charge](PlayerClient*, unsigned short, unsigned char)':
: undefined reference to `vtable for GripperProxy'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN13PositionProxyD1Ev+0xb): In function `PositionProxy::~PositionProxy [in-charge]()':
: undefined reference to `vtable for PositionProxy'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN13PositionProxyD1Ev+0x16): In function `PositionProxy::~PositionProxy [in-charge]()':
: undefined reference to `ClientProxy::~ClientProxy [not-in-charge]()'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN13PositionProxyC1EP12PlayerClientth+0x32): In function `PositionProxy::PositionProxy[in-charge](PlayerClient*, unsigned short, unsigned char)':
: undefined reference to `ClientProxy::ClientProxy[not-in-charge](PlayerClient*, unsigned short, unsigned short, unsigned char)'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN13PositionProxyC1EP12PlayerClientth+0x3e): In function `PositionProxy::PositionProxy[in-charge](PlayerClient*, unsigned short, unsigned char)':
: undefined reference to `vtable for PositionProxy'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN13PositionProxy8SetSpeedEii+0x12): In function `PositionProxy::SetSpeed(int, int)':
: undefined reference to `PositionProxy::SetSpeed(int, int, int)'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN10SonarProxyD1Ev+0xb): In function `SonarProxy::~SonarProxy [in-charge]()':
: undefined reference to `vtable for SonarProxy'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN10SonarProxyD1Ev+0x16): In function `SonarProxy::~SonarProxy [in-charge]()':
: undefined reference to `ClientProxy::~ClientProxy [not-in-charge]()'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN10SonarProxyC1EP12PlayerClientth+0x32): In function `SonarProxy::SonarProxy[in-charge](PlayerClient*, unsigned short, unsigned char)':
: undefined reference to `ClientProxy::ClientProxy[not-in-charge](PlayerClient*, unsigned short, unsigned short, unsigned char)'
/tmp/cc0PnmXM.o(.gnu.linkonce.t._ZN10SonarProxyC1EP12PlayerClientth+0x3e): In function `SonarProxy::SonarProxy[in-charge](PlayerClient*, unsigned short, unsigned char)':
: undefined reference to `vtable for SonarProxy'
collect2: ld returned 1 exit status

I really have no experience with g++, and no idea how to fix this... but i really need help, becuase a big grade depends on me writing this really big program, and so far im' not even able to compile using the player/stage libraries... not a good thing. Please help.

infamous41md · 12-28-2003, 12:58 AM

you need to give gcc the library to link to with the -l option. read up on 'man gcc' and the documents that came with your library. they should tell you the name of it. if they dont, have a look in the /usr/local/lib directory and find the name of the library file.
example:
libpthread.a is the file, so you give gcc this option 'gcc my_file.c -lpthread'

WanglessOlasov · 12-28-2003, 11:40 AM

I'm not sure i understand... the "-l" option takes a directory and a library, right? Well, these libraries are in /usr/local/lib/, but there are a lot of them, all called libplayer*.a, where "*" is just "client" or "packet" or something like that... there are about 5 or 6 of them. So you're saying that if this file is called "forage.cc", i would just do "g++ forage.cc -o forage -l/usr/local/lib/playerclient" ? See, what i don't understand is 1) there are more than one player libraries, so how do i know which one to name on the command line, and 2) if it's called "libplayerclient.a", do i just call it "playerclient" on the command line, or the full name of "libplayerclient.a"? Also, do i have to specify the directory, because you didn't, but the man page said it needed a directory... thanks for your help, but some elaboration would be appreciated. Like i said, i'm new to this, so i'm still sort of in the dark.

infamous41md · 12-28-2003, 12:18 PM

i'd just play around with all those until you find what works. you only need to use the libraries that define symbols you need. so if your program uses a symbol from every lib you mentioned, then you're gonna have to link all of them, or read the docs for the lib more closely.

infamous41md · 12-28-2003, 12:19 PM

http://www.linuxquestions.org/questi...hreadid=129226

^^like what i advised in there.

WanglessOlasov · 12-28-2003, 12:25 PM

YES! I got it! all i had to do was list the libraries, with no extra flags, after the source file, like this: "g++ forage.cc /usr/local/lib/libplayer* -o forage" and it worked! I have no idea why, but i'm not complaining. Thanks for your help.