On Mon, 2013-01-21 at 11:47 +0800, horseriver wrote: > what is the use of extern c within a declaration? That's a language question, not really a GCC question. Asking Google the question yields some good results, complete with examples: https://www.google.com/search?q=what+is+the+use+of+extern+c+within+a +declaration% 3F&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a