7.19.4.4 The tmpnam function

Synopsis

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#include <stdio.h>
char *tmpnam(char *s);

Description

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The tmpnam function generates a string that is a valid file name and that is not the same as the name of an existing file.[1] The function is potentially capable of generating TMP_MAX different strings, but any or all of them may already be in use by existing files and thus not be suitable return values.

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The tmpnam function generates a different string each time it is called.

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The implementation shall behave as if no library function calls the tmpnam function.

Returns

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If no suitable string can be generated, the tmpnam function returns a null pointer. Otherwise, if the argument is a null pointer, the tmpnam function leaves its result in an internal static object and returns a pointer to that object (subsequent calls to the tmpnam function may modify the same object). If the argument is not a null pointer, it is assumed to point to an array of at least L_tmpnam chars; the tmpnam function writes its result in that array and returns the argument as its value.

Environmental limits

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The value of the macro TMP_MAX shall be at least 25.

Footnotes

[1]

Files created using strings generated by the tmpnam function are temporary only in the sense that their names should not collide with those generated by conventional naming rules for the implementation. It is still necessary to use the remove function to remove such files when their use is ended, and before program termination.