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The TR 24731-1 {{tmpnam_s()}} function generates a string that is a valid filename and that is not the same as the name of an existing file \[[ISO/IEC TR 24731-1-2007|AA. C References#SO/IEC TR 24731-1-2007]\]. It is almost identical to the {{tmpnam{}}} function above except with an added {{maxsize}} argument for the supplied buffer.

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After a program obtains a file name using the tmpnam_s function and before the
program creates a file with that name, the possibility exists that someone else may create
a file with that same name. To avoid this race condition, the tmpfile_s function
should be used instead of tmpnam_s when possible. One situation that requires the use
of the tmpnam_s function is when the program needs to create a temporary directory
rather than a temporary file.

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