PROLOG | NAME | SYNOPSIS | DESCRIPTION | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

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

PROLOG         top

       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         top

       stdio.h — standard buffered input/output

SYNOPSIS         top

       #include <stdio.h>

DESCRIPTION         top

       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.1‐2008, 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         top

       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         top

       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         top

       None.

SEE ALSO         top

       stdarg.h(0p), stddef.h(0p), sys_types.h(0p)

       The System Interfaces volume of POSIX.1‐2008, Section 2.2, The
       Compilation Environment, clearerr(3p), ctermid(3p), fclose(3p),
       fdopen(3p), feof(3p), ferror(3p), fflush(3p), fgetc(3p), fgetpos(3p),
       fgets(3p), fileno(3p), flockfile(3p), fmemopen(3p), fopen(3p),
       fprintf(3p), fputc(3p), fputs(3p), fread(3p), freopen(3p),
       fscanf(3p), fseek(3p), fsetpos(3p), ftell(3p), fwrite(3p), getc(3p),
       getchar(3p), getc_unlocked(3p), getdelim(3p), getopt(3p), gets(3p),
       open_memstream(3p), pclose(3p), perror(3p), popen(3p), putc(3p),
       putchar(3p), puts(3p), remove(3p), rename(3p), rewind(3p),
       setbuf(3p), setvbuf(3p), stdin(3p), system(3p), tempnam(3p),
       tmpfile(3p), tmpnam(3p), ungetc(3p), vfprintf(3p), vfscanf(3p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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.unix.org/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                 2013                         stdio.h(0P)

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