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### 4.3 `fclose`—close a file

Synopsis

         #include <stdio.h>
         int fclose(FILE *fp);
         int _fclose_r(struct _reent *reent, FILE *fp);

Description
If the file or stream identified by fp is open, `fclose` closes it, after first ensuring that any pending data is written (by calling `fflush(`fp`)`).

The alternate function `_fclose_r` is a reentrant version. The extra argument reent is a pointer to a reentrancy structure.

Returns
`fclose` returns `0` if successful (including when fp is `NULL` or not an open file); otherwise, it returns `EOF`.

Portability
`fclose` is required by ANSI C.

Required OS subroutines: `close`, `fstat`, `isatty`, `lseek`, `read`, `sbrk`, `write`.