Where can I find the latest ANSI C standard document?
You can buy it here (ISO/IEC 9899:2011):
http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=57853
Price is around USD 240.
You can also get the latest (April 12, 2011) draft version for free:
http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf
UPDATE (June 16, 2016):
C11 has also been ratified by ANSI. The ANSI store is selling C11 document (essentially the same document as the ISO one) for a cheaper price: USD 60 (as of June 16, 2016).
ISO store also lowered their price for C11, from CHF 238 to CHF 198 (around USD 205, as of June 16, 2016).
来源：https://stackoverflow.com/questions/11504312/where-to-get-the-latest-ansi-c-standard-document