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Where do I find the current C or C++ standard documents?
Where can I read C99 official language standard manual/reference/specification online?
The official standard should not be available online — ISO and its national standards bodies would be unhappy about that. You can obtain an official electronic copy from the ANSI store (http://webstore.ansi.org/) for $18 $30 (or thereabouts — it was $18 when I obtained the C99 standard, but that was quite a while ago now; it was $30 for the C11 standard). Or you can go to the web site linked in other answers (and via Wikipedia) — namely http://www.open-std.org/jtc1/sc22/wg14/ - and obtain almost official copies of the standards documents.