Question

I’m writing a software that depends on the Poco c++ library. I can manage to compile the library on both Ubuntu and Windows, but only as static. That’s fine since I want to use it statically. However, when I try to compile the program that depends on the libraries, I get an error similar to this (freely translated) :

Poco/RegularExpression.h: No such file or directory.

However, when I also explicitly tells the compiler where to look for the library’s header files with the -I switch I get the following error instead (but maybe 20-30 similar lines) :

Undefined reference to (pthread_mutex...)

I’ve tried with a lot of different combinations, both directly with g++, and by using makefiles.
Am I supposed to include the paths to the libraries’ header files, or have I somehow not succeeded to compile the libraries properly?
If I should include the paths, how can I get rid of the “undefined reference” error?

I’m pretty new with c++ programming so bear with me.
Thanks, Robert

Answer 1

This is very common error, I, too, suffer from it every now and then.

• Did you include the .a to your project?
• How do you include the headers? with <> or “”?
  • If the latter, make sure the files are in your include folder.
  • If first, make sure you have added the path to the files, or that they reside in g++’s global include folder
• Is the library meant to be compiled as .so/.dll?
  • Normally if the library is meant to be dynamic, the static library only points to it.
• Do you have included the dependencies the Poco itself requires? Like the -lpthread I think you are missing.