Using the value of a pointer to a FILE object after the associated file is closed is undefined behavior. (See undefined behavior 148153.) Programs that close the standard streams (especially stdout but also stderr and stdin) must be careful not to use these streams in subsequent function calls, particularly those that implicitly operate on them (such as printf(), perror(), and getc()).
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| [IEEE Std 1003.1:2013] | XSH, System Interfaces, open |
| [ISO/IEC 9899:20112024] | Subclause 7.2123.3, "Files" |
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