stdio.h(0P)		   POSIX Programmer's Manual		   stdio.h(0P)

PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The Linux
       implementation of this interface may differ (consult the corresponding
       Linux manual page for details of Linux behavior), or the interface may
       not be implemented on Linux.

NAME
       stdio.h — standard buffered input/output

SYNOPSIS
       #include <stdio.h>

DESCRIPTION
       Some of the functionality described on this reference page extends the
       ISO C standard. Applications shall define the appropriate feature test
       macro (see the System Interfaces volume of POSIX.1‐2017, Section 2.2,
       The Compilation Environment) to enable the visibility of these symbols
       in this header.

       The <stdio.h> header shall define the following data types through
       typedef:

       FILE	     A structure containing information about a file.

       fpos_t	     A non-array type containing all information needed to
		     specify uniquely every position within a file.

       off_t	     As described in <sys/types.h>.

       size_t	     As described in <stddef.h>.

       ssize_t	     As described in <sys/types.h>.

       va_list	     As described in <stdarg.h>.

       The <stdio.h> header shall define the following macros which shall
       expand to integer constant expressions:

       BUFSIZ	     Size of <stdio.h> buffers.	 This shall expand to a
		     positive value.

       L_ctermid     Maximum size of character array to hold ctermid() output.

       L_tmpnam	     Maximum size of character array to hold tmpnam() output.

       The <stdio.h> header shall define the following macros which shall
       expand to integer constant expressions with distinct values:

       _IOFBF	     Input/output fully buffered.

       _IOLBF	     Input/output line buffered.

       _IONBF	     Input/output unbuffered.

       The <stdio.h> header shall define the following macros which shall
       expand to integer constant expressions with distinct values:

       SEEK_CUR	     Seek relative to current position.

       SEEK_END	     Seek relative to end-of-file.

       SEEK_SET	     Seek relative to start-of-file.

       The <stdio.h> header shall define the following macros which shall
       expand to integer constant expressions denoting implementation limits:

       {FILENAME_MAX}
		     Maximum size in bytes of the longest pathname that the
		     implementation guarantees can be opened.

       {FOPEN_MAX}   Number of streams which the implementation guarantees can
		     be open simultaneously. The value is at least eight.

       {TMP_MAX}     Minimum number of unique filenames generated by tmpnam().
		     Maximum number of times an application can call tmpnam()
		     reliably. The value of {TMP_MAX} is at least 25.

		     On XSI-conformant systems, the value of {TMP_MAX} is at
		     least 10000.

       The <stdio.h> header shall define the following macro which shall
       expand to an integer constant expression with type int and a negative
       value:

       EOF	     End-of-file return value.

       The <stdio.h> header shall define NULL as described in <stddef.h>.

       The <stdio.h> header shall define the following macro which shall
       expand to a string constant:

       P_tmpdir	     Default directory prefix for tempnam().

       The <stdio.h> header shall define the following macros which shall
       expand to expressions of type ``pointer to FILE'' that point to the
       FILE objects associated, respectively, with the standard error, input,
       and output streams:

       stderr	     Standard error output stream.

       stdin	     Standard input stream.

       stdout	     Standard output stream.

       The following shall be declared as functions and may also be defined as
       macros. Function prototypes shall be provided.


	   void	    clearerr(FILE *);
	   char	   *ctermid(char *);
	   int	    dprintf(int, const char *restrict, ...)
	   int	    fclose(FILE *);
	   FILE	   *fdopen(int, const char *);
	   int	    feof(FILE *);
	   int	    ferror(FILE *);
	   int	    fflush(FILE *);
	   int	    fgetc(FILE *);
	   int	    fgetpos(FILE *restrict, fpos_t *restrict);
	   char	   *fgets(char *restrict, int, FILE *restrict);
	   int	    fileno(FILE *);
	   void	    flockfile(FILE *);
	   FILE	   *fmemopen(void *restrict, size_t, const char *restrict);
	   FILE	   *fopen(const char *restrict, const char *restrict);
	   int	    fprintf(FILE *restrict, const char *restrict, ...);
	   int	    fputc(int, FILE *);
	   int	    fputs(const char *restrict, FILE *restrict);
	   size_t   fread(void *restrict, size_t, size_t, FILE *restrict);
	   FILE	   *freopen(const char *restrict, const char *restrict,
			FILE *restrict);
	   int	    fscanf(FILE *restrict, const char *restrict, ...);
	   int	    fseek(FILE *, long, int);
	   int	    fseeko(FILE *, off_t, int);
	   int	    fsetpos(FILE *, const fpos_t *);
	   long	    ftell(FILE *);
	   off_t    ftello(FILE *);
	   int	    ftrylockfile(FILE *);
	   void	    funlockfile(FILE *);
	   size_t   fwrite(const void *restrict, size_t, size_t, FILE *restrict);
	   int	    getc(FILE *);
	   int	    getchar(void);
	   int	    getc_unlocked(FILE *);
	   int	    getchar_unlocked(void);
	   ssize_t  getdelim(char **restrict, size_t *restrict, int,
			FILE *restrict);
	   ssize_t  getline(char **restrict, size_t *restrict, FILE *restrict);
	   char	   *gets(char *);
	   FILE	   *open_memstream(char **, size_t *);
	   int	    pclose(FILE *);
	   void	    perror(const char *);
	   FILE	   *popen(const char *, const char *);
	   int	    printf(const char *restrict, ...);
	   int	    putc(int, FILE *);
	   int	    putchar(int);
	   int	    putc_unlocked(int, FILE *);
	   int	    putchar_unlocked(int);
	   int	    puts(const char *);
	   int	    remove(const char *);
	   int	    rename(const char *, const char *);
	   int	    renameat(int, const char *, int, const char *);
	   void	    rewind(FILE *);
	   int	    scanf(const char *restrict, ...);
	   void	    setbuf(FILE *restrict, char *restrict);
	   int	    setvbuf(FILE *restrict, char *restrict, int, size_t);
	   int	    snprintf(char *restrict, size_t, const char *restrict, ...);
	   int	    sprintf(char *restrict, const char *restrict, ...);
	   int	    sscanf(const char *restrict, const char *restrict, ...);
	   char	   *tempnam(const char *, const char *);
	   FILE	   *tmpfile(void);
	   char	   *tmpnam(char *);
	   int	    ungetc(int, FILE *);
	   int	    vdprintf(int, const char *restrict, va_list);
	   int	    vfprintf(FILE *restrict, const char *restrict, va_list);
	   int	    vfscanf(FILE *restrict, const char *restrict, va_list);
	   int	    vprintf(const char *restrict, va_list);
	   int	    vscanf(const char *restrict, va_list);
	   int	    vsnprintf(char *restrict, size_t, const char *restrict,
			va_list);
	   int	    vsprintf(char *restrict, const char *restrict, va_list);
	   int	    vsscanf(const char *restrict, const char *restrict, va_list);

       Inclusion of the <stdio.h> header may also make visible all symbols
       from <stddef.h>.

       The following sections are informative.

APPLICATION USAGE
       Since standard I/O streams may use an underlying file descriptor to
       access the file associated with a stream, application developers need
       to be aware that {FOPEN_MAX} streams may not be available if file
       descriptors are being used to access files that are not associated with
       streams.

RATIONALE
       There is a conflict between the ISO C standard and the POSIX definition
       of the {TMP_MAX} macro that is addressed by ISO/IEC 9899:1999 standard,
       Defect Report 336. The POSIX standard is in alignment with the public
       record of the response to the Defect Report.  This change has not yet
       been published as part of the ISO C standard.

FUTURE DIRECTIONS
       None.

SEE ALSO
       <stdarg.h>, <stddef.h>, <sys_types.h>

       The System Interfaces volume of POSIX.1‐2017, Section 2.2, The
       Compilation Environment, clearerr(), ctermid(), fclose(), fdopen(),
       feof(), ferror(), fflush(), fgetc(), fgetpos(), fgets(), fileno(),
       flockfile(), fmemopen(), fopen(), fprintf(), fputc(), fputs(), fread(),
       freopen(), fscanf(), fseek(), fsetpos(), ftell(), fwrite(), getc(),
       getchar(), getc_unlocked(), getdelim(), getopt(), gets(),
       open_memstream(), pclose(), perror(), popen(), putc(), putchar(),
       puts(), remove(), rename(), rewind(), setbuf(), setvbuf(), stdin,
       system(), tempnam(), tmpfile(), tmpnam(), ungetc(), vfprintf(),
       vfscanf()

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  In the event of any discrepancy between this version and the
       original IEEE and The Open Group Standard, the original IEEE and The
       Open Group Standard is the referee document. The original Standard can
       be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group		     2017			   stdio.h(0P)