How to compile and link a C/C++ shared object library in the right way?

Question

I have developed a C++ class which reads in a text file and store some information in provate variables. To parse the file, I use regex library. During compilation there is an error I can't understand. First I make a shared object library for my class. Afterwards I try to compile the test program. Here the error occurs: undefined reference to std::regex_iterator...

I do the compilation with the following commands on a unix machine:

g++ -c -fpic -m64 -std=c++11 Foo.h Foo.cpp

g++ -shared -m64 -std=c++11 -o libFoo.so Foo.o

g++ -m64 -std=c++11 -I. -L. -lFoo -o camelTest Foo.h main.cpp

To reproduce the error, here is a small example: example

Thanks in advance for your help

Which version of GCC are you using? GCC haven't supported the regular expressions in the standard library until quite recently. — Some programmer dude, Aug 01 '14 at 09:00
I do not know if regex is supported by C++, but I think so. The error also occurs when I do not include Foo.h in the last command. — Fabian, Aug 01 '14 at 09:01
@JonathanWakely: Is there a document somewhere explaining the particular implementation strategy of GCC's regexp implementation? I take it that this is a somewhat delicate topic, and users may wish to know about the details before deciding to move a project from their own regexp library to the standard version. — Kerrek SB, Aug 01 '14 at 09:07
@KerrekSB, the only notes on the design are on the libstdc++ mailing list, look for posts by Tim Shen who finished the regex implementation — Jonathan Wakely, Aug 01 '14 at 09:09

Edward · Answer 1 · 2014-08-01T08:59:28.910

0

g++ -m64 -std=c++11 -I. -L. -lFoo -o camelTest Foo.h main.cpp -L%PATH_TO_USED_LIB% -l%NAME_OF_LIB%

If your lib is libregexp, then %NAME_OF_LIB% == regexp

The idea is:

Flag -L(uppercase) tells gcc where your libs are.

Flag l(lowercase) tells gcc which library should gcc link to your application.

edited Aug 01 '14 at 08:59

answered Aug 01 '14 at 08:54

Edward

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I thought that the regex lib is in LD_LIBRARY_PATH located. – Fabian Aug 01 '14 at 09:00
Which version of gcc are you using? – Edward Aug 01 '14 at 09:04
if version of your gcc is lower than 4.9.0 then there is bug(regexp functionality is **not** implemented: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53631 – Edward Aug 01 '14 at 09:06

How to compile and link a C/C++ shared object library in the right way?

1 Answers1