stdio/fgetln.3

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  32 .\"     @(#)fgetln.3    8.3 (Berkeley) 4/19/94
  33 .\" $FreeBSD: src/lib/libc/stdio/fgetln.3,v 1.7 2001/10/01 16:08:59 ru Exp $
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  35 .Dd April 19, 1994
  36 .Dt FGETLN 3
  37 .Os
  38 .Sh NAME
  39 .Nm fgetln
  40 .Nd get a line from a stream
  41 .Sh LIBRARY
  42 .Lb libc
  43 .Sh SYNOPSIS
  44 .In stdio.h
  45 .Ft char *
  46 .Fn fgetln "FILE *stream" "size_t *len"
  47 .Sh DESCRIPTION
  48 The
  49 .Fn fgetln
  50 function
  51 returns a pointer to the next line from the stream referenced by
  52 .Fa stream .
  53 This line is
  54 .Em not
  55 a C string as it does not end with a terminating
  56 .Dv NUL
  57 character.
  58 The length of the line, including the final newline,
  59 is stored in the memory location to which
  60 .Fa len
  61 points.
  62 (Note, however, that if the line is the last
  63 in a file that does not end in a newline,
  64 the returned text will not contain a newline.)
  65 .Sh RETURN VALUES
  66 Upon successful completion a pointer is returned;
  67 this pointer becomes invalid after the next
  68 .Tn I/O
  69 operation on
  70 .Fa stream
  71 (whether successful or not)
  72 or as soon as the stream is closed.
  73 Otherwise,
  74 .Dv NULL
  75 is returned.
  76 The
  77 .Fn fgetln
  78 function
  79 does not distinguish between end-of-file and error; the routines
  80 .Xr feof 3
  81 and
  82 .Xr ferror 3
  83 must be used
  84 to determine which occurred.
  85 If an error occurs, the global variable
  86 .Va errno
  87 is set to indicate the error.
  88 The end-of-file condition is remembered, even on a terminal, and all
  89 subsequent attempts to read will return
  90 .Dv NULL
  91 until the condition is
  92 cleared with
  93 .Xr clearerr 3 .
  94 .Pp
  95 The text to which the returned pointer points may be modified,
  96 provided that no changes are made beyond the returned size.
  97 These changes are lost as soon as the pointer becomes invalid.
  98 .Sh ERRORS
  99 .Bl -tag -width Er
 100 .It Bq Er EBADF
 101 The argument
 102 .Fa stream
 103 is not a stream open for reading.
 104 .El
 105 .Pp
 106 The
 107 .Fn fgetln
 108 function
 109 may also fail and set
 110 .Va errno
 111 for any of the errors specified for the routines
 112 .Xr fflush 3 ,
 113 .Xr malloc 3 ,
 114 .Xr read 2 ,
 115 .Xr stat 2 ,
 116 or
 117 .Xr realloc 3 .
 118 .Sh SEE ALSO
 119 .Xr ferror 3 ,
 120 .Xr fgets 3 ,
 121 .Xr fopen 3 ,
 122 .Xr putc 3
 123 .Sh HISTORY
 124 The
 125 .Fn fgetln
 126 function first appeared in
 127 .Bx 4.4 .