In linux, how does one know the library name when gcc is used to compile c?

For example, # include <math. h>
So gcc-lm can be found online
What if it is # include <string. h>? Direct-lstring does not seem to work.
Or something else? I don't know where to find the name of the Library in gcc compilation from the document.

--- This is generally required by math and pthread.
Other standard libraries are implemented in glibc, and gcc will be linked by default.

--- Glibc is the gnu Implementation of libc.
String should be regarded as the C standard. The default connected libc. so seems to include all the C Standard functions.

From: http://bbs.chinaunix.net/thread-1677645-1-1.html