Writing/Using C++ Libraries

Question

I am looking for basic examples/tutorials on:

How to write/compile libraries in C++ (.so files for Linux, .dll files for Windows).
How to import and use those libraries in other code.

worth a look - also covers static vs dynamic libraries : learncpp.com/cpp-tutorial/a1-static-and-dynamic-libraries — Graham Griffiths
– Graham Griffiths, Commented Aug 20, 2013 at 13:14
also this for code to dynamically load a shared library (with dlopen) : stackoverflow.com/questions/496664/… — Graham Griffiths
– Graham Griffiths, Commented Aug 20, 2013 at 13:17

wilhelmtell · Accepted Answer · 2008-09-04 03:43:18Z

18

The code

r.cc :

#include "t.h" int main() { f(); return 0; }

t.h :

void f();

t.cc :

#include<iostream> #include "t.h" void f() { std::cout << "OH HAI. I'M F." << std::endl; }

But how, how, how?!

~$ g++ -fpic -c t.cc # get t.o ~$ g++ -shared -o t.so t.o # get t.so ~$ export LD_LIBRARY_PATH="." # make sure t.so is found when dynamically linked ~$ g++ r.cc t.so # get an executable

The export step is not needed if you install the shared library somewhere along the global library path.

edited Sep 4, 2008 at 3:43

answered Sep 3, 2008 at 23:18

wilhelmtell

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6 Comments

rubenvb Over a year ago

This is a terrible explanation. It doesn' work on Windows, doesn't even touch what Windows adds to this, and throws away everything that was in LD_LIBRARY_PATH...

Maxim Egorushkin Over a year ago

@rubenvb It does work on windows. You need to install cygwin.

Maxim Egorushkin Over a year ago

Instead of LD_LIBRARY_PATH use g++ -Wl,-rpath,\$ORIGIN r.cc t.so.

rubenvb Over a year ago

@Maxim Cygwin != Windows. And Cygwin needs dllexport nonetheless.

Ajay Over a year ago

@rubenvb your point about LD_LIBRARY_PATH should be cleared up a bit. This doesn't overwrite it permanently, because all of these changes would be local to that particular shell. Assuming this would be in a makefile for a realistic problem it would only make changes in the subshell spawned by make. This is still not the best way to do it, but for those who may get confused this wont ruin your compiler forever.

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