how to choose libc6 or libc6-dbg

Im bug checking a c program and would like to install valgrind, the system then tells me that I should also install libc6 with debug symbols libc6-dbg.

Now my question is, when I in the future compile with gcc, which version of libc will be used?

How do I choose which libc6 I'm compilin开发者_Python百科g against?

I'm not asking how to install this, I'm on ubuntu so apt-get install libc6-dbg will do the trick.

libc6-dbg is not a separate library from libc6 — it's the debugging symbols for libc6, so that you can get accurate tracebacks within libc.