libc

$ ldd a.out
    linux-vdso.so.1 =>  (0x00007fd7ea05b000)
    libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fd7e9c66000)
    /lib64/ld-linux-x86-64.so.2 (0x00005604828b7000)
$

$ /lib/{x86_64-linux-gnu}/libc.so.6
GNU C Library (Ubuntu GLIBC 2.23-0ubuntu10) stable release version 2.23, by Roland McGrath et al.
Copyright (C) 2016 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.
Compiled by GNU CC version 5.4.0 20160609.
Available extensions:
    crypt add-on version 2.1 by Michael Glad and others
    GNU Libidn by Simon Josefsson
    Native POSIX Threads Library by Ulrich Drepper et al
    BIND-8.2.3-T5B
libc ABIs: UNIQUE IFUNC
For bug reporting instructions, please see:
<https://bugs.launchpad.net/ubuntu/+source/glibc/+bugs>.

$
 

printf("%d, %d\n", __GLIBC__, __GLIBC_MINOR__); // 2, 23

#include <gnu/libc-version.h>
printf("%s\n", gnu_get_libc_version()); // 2.23

size_t unsigned int/unsigned long
ssize_t int/long
uid_t unsigned int

pid_t int
off_t long
dev_t u32

typedef unsigned long		uintptr_t;