Do we use libstdc++.a and libstdc++.so at the same time when generating executable?

Question

If I choose to do:

gcc my.cpp -lstdc++

It links with libstdc++.so, right? But there're some c/c++ initialization part of code(global/static variables/objects, atexit() functions, etc), seems they should also require linking to libstdc++.a file.

So my question is, does the linking command always uses libstdc++.a for some reason, even if I specified to link with .so file?

Thanks.

Answer 1

gcc my.cpp -lstdc++

This is usually the wrong thing to do. Instead, you should do this:

g++ my.cpp

It links with libstdc++.so, right?

Depends on how GCC was configured and installed, but most often yes.

But there're some c/c++ initialization part of code(global/static variables/objects, atexit() functions, etc), seems they should also require linking to libstdc++.a file.

This is false. Where did you get this mistaken impression from?

So my question is, does the linking command always uses libstdc++.a

No, not usually.

Answer 2

If you use g++ test.cpp it links against "libstdc++" (defaults to the shared library if present, libstdc++.so) if you run g++ -static-libstdc++ test.cpp then it links against listdc++.a if possible. Or g++ -static which happens to imply -static-libstdc++