gets(3) [netbsd man page]

FGETS(3)						   BSD Library Functions Manual 						  FGETS(3)

NAME

     fgets, gets -- get a line from a stream

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <stdio.h>

     char *
     fgets(char * restrict str, int size, FILE * restrict stream);

     char *
     gets(char *str);

DESCRIPTION

     The fgets() function reads at most one less than the number of characters specified by size from the given stream and stores them in the
     string str.  Reading stops when a newline character is found, at end-of-file or error.  The newline, if any, is retained, and a '' charac-
     ter is appended to end the string.

     The gets() function is equivalent to fgets() with an infinite size and a stream of stdin, except that the newline character (if any) is not
     stored in the string.  It is the caller's responsibility to ensure that the input line, if any, is sufficiently short to fit in the string.

RETURN VALUES

     Upon successful completion, fgets() and gets() return a pointer to the string.  If end-of-file or an error occurs before any characters are
     read, they return NULL.  The fgets() and gets() functions do not distinguish between end-of-file and error, and callers must use feof(3) and
     ferror(3) to determine which occurred.

ERRORS

     [EBADF]		The given stream is not a readable stream.

     The function fgets() may also fail and set errno for any of the errors specified for the routines fflush(3), fstat(2), read(2), or malloc(3).

     The function gets() may also fail and set errno for any of the errors specified for the routine getchar(3).

SEE ALSO

     feof(3), ferror(3), fgetln(3)

STANDARDS

     The functions fgets() and gets() conform to ANSI X3.159-1989 (``ANSI C89'') and IEEE Std 1003.1-2001 (``POSIX.1'').  The IEEE Std 1003.1-2008
     (``POSIX.1'') revision marked gets() as obsolescent.

CAVEATS

     The following bit of code illustrates a case where the programmer assumes a string is too long if it does not contain a newline:

	     char buf[1024], *p;

	     while (fgets(buf, sizeof(buf), fp) != NULL) {
		     if ((p = strchr(buf, '
')) == NULL) {
			     fprintf(stderr, "input line too long.
");
			     exit(1);
		     }
		     *p = '';
		     printf("%s
", buf);
	     }

     While the error would be true if a line longer than 1023 characters were read, it would be false in two other cases:

	   1.	If the last line in a file does not contain a newline, the string returned by fgets() will not contain a newline either.  Thus
		strchr() will return NULL and the program will terminate, even if the line was valid.

	   2.	All C string functions, including strchr(), correctly assume the end of the string is represented by a null ('') character.  If
		the first character of a line returned by fgets() were null, strchr() would immediately return without considering the rest of the
		returned text which may indeed include a newline.

     Consider using fgetln(3) instead when dealing with untrusted input.

SECURITY CONSIDERATIONS

     Since it is usually impossible to ensure that the next input line is less than some arbitrary length, and because overflowing the input buf-
     fer is almost invariably a security violation, programs should NEVER use gets().  The gets() function exists purely to conform to ANSI
     X3.159-1989 (``ANSI C89'').

BSD
								   May 13, 2010 							       BSD

Check Out this Related Man Page

FGETS(P)						     POSIX Programmer's Manual							  FGETS(P)

NAME

       fgets - get a string from a stream

SYNOPSIS

       #include <stdio.h>

       char *fgets(char *restrict s, int n, FILE *restrict stream);

DESCRIPTION

       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 st_atime field of the file associated with stream for update. The st_atime  field  shall  be  marked  for
       update  by the first successful execution of fgetc(), fgets(), fgetwc(), fgetws(), fread(), fscanf(), getc(), getchar(), gets(), or scanf()
       using stream that returns data not supplied by a prior call to ungetc() or ungetwc().

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 each line of input.  {LINE_MAX}, which defines the maximum size of the input line, is defined in
       the <limits.h> header.

	      #include <stdio.h>
	      ...
	      char line[LINE_MAX];
	      ...
	      while (fgets(line, LINE_MAX, fp) != NULL) {
	      ...
	      }
	      ...

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       fopen() , fread() , gets() , the Base Definitions volume of IEEE Std 1003.1-2001, <stdio.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 .

IEEE
/The Open Group						       2003								  FGETS(P)

Linux and UNIX Man Pages

gets(3) [netbsd man page]

Check Out this Related Man Page