NAME
    fclose - close a file

SYNOPSIS
    fclose(fd)

TYPES
    fd		file

    return	nul or int

DESCRIPTION
    This function closes the open file associated with the descriptor fd.
    When this is done, the file value associated with the file remains
    a file value, but appears 'closed', and cannot be used in further
    file-related calls (except fclose) without causing errors.	This same
    action occurs to all copies of the file value.  You do not need to
    explicitly close all the copies of a file value.

    Standard input, standard output and standard error are always opened
    and cannot be closed.

    The truth value of an closed file is FALSE.

    The fclose function returns the numeric value of errno if
    there had been an error using the file, or the null value if
    there was no error.

    Closing a closed file is permitted.	 Fclose returns null in
    this case.

EXAMPLE
    > fd = fopen("/etc/motd", "r")
    > if (fd) print "file is open";
    file is open

    > err = fclose(fd);
    > if (isnull(err)) print "close successful"; else errno(err);
    close successful

    > if (!fd) print "file is closed";
    file is closed

LIMITS
    fd != files(0) && fd != files(1) && fd != files(2)

LIBRARY
    none

SEE ALSO
    errno, fclose, feof, ferror, fflush, fgetc, fgetline, fgets, files, fopen,
    fprintf, fputc, fputs, fseek, fsize, ftell, isfile, printf, prompt