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FGETS(3P)                  POSIX Programmer's Manual                 FGETS(3P)
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
       fgets -- get a string from a stream
SYNOPSIS
       #include <stdio.h>
       char *fgets(char *restrict s, int n, FILE *restrict stream);
DESCRIPTION
       The functionality described on this reference page is aligned with  the
       ISO C  standard.  Any  conflict between the requirements described here
       and the ISO C standard is unintentional. This  volume  of  POSIX.1-2008
       defers to the ISO C standard.
       The  fgets()  function  shall  read  bytes  from  stream into the array
       pointed to by s, until n-1 bytes are read, or a <newline> is  read  and
       transferred  to  s,  or  an  end-of-file  condition is encountered. The
       string is then terminated with a null byte.
       The fgets() function may mark the last data  access  timestamp  of  the
       file  associated with stream for update. The last data access timestamp
       shall be marked  for  update  by  the  first  successful  execution  of
       fgetc(),  fgets(),  fread(),  fscanf(),  getc(), getchar(), getdelim(),
       getline(), gets(), or scanf() using stream that returns data  not  sup-
       plied by a prior call to ungetc().
RETURN VALUE
       Upon  successful  completion, fgets() shall return s.  If the stream is
       at end-of-file, the end-of-file indicator for the stream shall  be  set
       and  fgets()  shall return a null pointer.  If a read error occurs, the
       error indicator for the stream shall be set,  fgets()  shall  return  a
       null pointer, and shall set errno to indicate the error.
ERRORS
       Refer to fgetc().
       The following sections are informative.
EXAMPLES
   Reading Input
       The  following  example uses fgets() to read lines of input. It assumes
       that the file it is reading is a text file and that lines in this  text
       file  are  no longer than 16384 (or {LINE_MAX} if it is less than 16384
       on the implementation where it is running) bytes long. (Note  that  the
       standard  utilities  have no line length limit if sysconf(_SC_LINE_MAX)
       returns  -1  without  setting  errno.   This   example   assumes   that
       sysconf(_SC_LINE_MAX) will not fail.)
           #include <limits.h>
           #include <stdio.h>
           #include <unistd.h>
           #define MYLIMIT 16384
           char *line;
           int line_max;
           if (LINE_MAX >= MYLIMIT) {
               // Use maximum line size of MYLIMIT. If LINE_MAX is
               // bigger than our limit, sysconf() can't report a
               // smaller limit.
               line_max = MYLIMIT;
           } else {
               long limit = sysconf(_SC_LINE_MAX);
               line_max = (limit < 0 || limit > MYLIMIT) ? MYLIMIT : (int)limit;
           }
           // line_max + 1 leaves room for the null byte added by fgets().
           line = malloc(line_max + 1);
           if (line == NULL) {
               // out of space
               ...
               return error;
           }
           while (fgets(line, line_max + 1, fp) != NULL) {
               // Verify that a full line has been read ...
               // If not, report an error or prepare to treat the
               // next time through the loop as a read of a
               // continuation of the current line.
               ...
               // Process line ...
               ...
           }
           free(line);
           ...
APPLICATION USAGE
       None.
RATIONALE
       None.
FUTURE DIRECTIONS
       None.
SEE ALSO
       Section 2.5, Standard I/O Streams, fgetc(), fopen(), fread(), fscanf(),
       getc(), getchar(), getdelim(), gets(), ungetc()
       The Base Definitions volume of POSIX.1-2008, <stdio.h>
COPYRIGHT
       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 Electri-
       cal 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.ker-
       nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group                  2013                            FGETS(3P)