4 (3.2.5 [IBM XL C Compiler])
8 (3.x [Apple C Compiler, GNU C])
11 <a href="http://www.freebsd.org/">FreeBSD</a>
12 (4.5 and newer on i386, x86_64 [GNU C])
15 <a href="http://www.hp.com/">HP-UX</a>
16 (9.10, 10.20, 11.11 on hppa, m68k [HP-UX cc, GNU C])
20 (6.5 [SGI MIPSpro C 7.30])
23 <a href="http://www.linux.org/">Linux</a>
24 (2.x.y, 3.x on hppa, i386, mipsel, powerpc, x86_64, ... [GNU C])
27 <a href="http://www.apple.com/macosx/">Mac OS X</a> (Darwin)
28 (10.0 and newer on i386, powerpc, x86_64 [GNU C 2.95.x, 3.x, 4.x])
31 <a href="http://www.netbsd.org/">NetBSD</a>
32 (1.5.2 and newer on alpha, i386, m68k, sparc, x86_64, ... [GNU C])
35 <a href="http://www.obenbsd.org/">OpenBSD</a>
36 (3.4 and newer on hppa, i386, powerpc, x86_64 [GNU C])
39 <a href="http://www.sun.com/">Solaris</a>
40 (2.5.1 and newer on i386, sparc [GNU C])
43 Windows mit <a href="http://sources.redhat.com/cygwin/">Cygwin</a>