stdio/FreeBSD/getc.3

   1 .\" Copyright (c) 1990, 1991, 1993
   2 .\"     The Regents of the University of California.  All rights reserved.
   3 .\"
   4 .\" This code is derived from software contributed to Berkeley by
   5 .\" Chris Torek and the American National Standards Committee X3,
   6 .\" on Information Processing Systems.
   7 .\"
   8 .\" Redistribution and use in source and binary forms, with or without
   9 .\" modification, are permitted provided that the following conditions
  10 .\" are met:
  11 .\" 1. Redistributions of source code must retain the above copyright
  12 .\"    notice, this list of conditions and the following disclaimer.
  13 .\" 2. Redistributions in binary form must reproduce the above copyright
  14 .\"    notice, this list of conditions and the following disclaimer in the
  15 .\"    documentation and/or other materials provided with the distribution.
  16 .\" 4. Neither the name of the University nor the names of its contributors
  17 .\"    may be used to endorse or promote products derived from this software
  18 .\"    without specific prior written permission.
  19 .\"
  20 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  21 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23 .\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  24 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30 .\" SUCH DAMAGE.
  31 .\"
  32 .\"     @(#)getc.3      8.1 (Berkeley) 6/4/93
  33 .\" $FreeBSD: src/lib/libc/stdio/getc.3,v 1.21 2007/01/09 00:28:06 imp Exp $
  34 .\"
  35 .Dd January 10, 2003
  36 .Dt GETC 3
  37 .Os
  38 .Sh NAME
  39 .Nm fgetc ,
  40 .Nm getc ,
  41 .Nm getc_unlocked ,
  42 .Nm getchar ,
  43 .Nm getchar_unlocked ,
  44 .Nm getw
  45 .Nd get next character or word from input stream
  46 .Sh LIBRARY
  47 .Lb libc
  48 .Sh SYNOPSIS
  49 .In stdio.h
  50 .Ft int
  51 .Fn fgetc "FILE *stream"
  52 .Ft int
  53 .Fn getc "FILE *stream"
  54 .Ft int
  55 .Fn getc_unlocked "FILE *stream"
  56 .Ft int
  57 .Fn getchar "void"
  58 .Ft int
  59 .Fn getchar_unlocked "void"
  60 .Ft int
  61 .Fn getw "FILE *stream"
  62 .Sh DESCRIPTION
  63 The
  64 .Fn fgetc
  65 function
  66 obtains the next input character (if present) from the stream pointed at by
  67 .Fa stream ,
  68 or the next character pushed back on the stream via
  69 .Xr ungetc 3 .
  70 .Pp
  71 The
  72 .Fn getc
  73 function
  74 acts essentially identically to
  75 .Fn fgetc ,
  76 but is a macro that expands in-line.
  77 .Pp
  78 The
  79 .Fn getchar
  80 function
  81 is equivalent to
  82 .Fn getc stdin .
  83 .Pp
  84 The
  85 .Fn getw
  86 function
  87 obtains the next
  88 .Vt int
  89 (if present)
  90 from the stream pointed at by
  91 .Fa stream .
  92 .Pp
  93 The
  94 .Fn getc_unlocked
  95 and
  96 .Fn getchar_unlocked
  97 functions are equivalent to
  98 .Fn getc
  99 and
 100 .Fn getchar
 101 respectively,
 102 except that the caller is responsible for locking the stream
 103 with
 104 .Xr flockfile 3
 105 before calling them.
 106 These functions may be used to avoid the overhead of locking the stream
 107 for each character, and to avoid input being dispersed among multiple
 108 threads reading from the same stream.
 109 .Sh RETURN VALUES
 110 If successful, these routines return the next requested object
 111 from the
 112 .Fa stream .
 113 Character values are returned as an
 114 .Vt "unsigned char"
 115 converted to an
 116 .Vt int .
 117 If the stream is at end-of-file or a read error occurs,
 118 the routines return
 119 .Dv EOF .
 120 The routines
 121 .Xr feof 3
 122 and
 123 .Xr ferror 3
 124 must be used to distinguish between end-of-file and error.
 125 If an error occurs, the global variable
 126 .Va errno
 127 is set to indicate the error.
 128 The end-of-file condition is remembered, even on a terminal, and all
 129 subsequent attempts to read will return
 130 .Dv EOF
 131 until the condition is cleared with
 132 .Xr clearerr 3 .
 133 .Sh SEE ALSO
 134 .Xr ferror 3 ,
 135 .Xr flockfile 3 ,
 136 .Xr fopen 3 ,
 137 .Xr fread 3 ,
 138 .Xr getwc 3 ,
 139 .Xr putc 3 ,
 140 .Xr ungetc 3
 141 .Sh STANDARDS
 142 The
 143 .Fn fgetc ,
 144 .Fn getc ,
 145 and
 146 .Fn getchar
 147 functions
 148 conform to
 149 .St -isoC .
 150 The
 151 .Fn getc_unlocked
 152 and
 153 .Fn getchar_unlocked
 154 functions conform to
 155 .St -p1003.1-2001 .
 156 .Sh BUGS
 157 Since
 158 .Dv EOF
 159 is a valid integer value,
 160 .Xr feof 3
 161 and
 162 .Xr ferror 3
 163 must be used to check for failure after calling
 164 .Fn getw .
 165 The size and byte order of an
 166 .Vt int
 167 varies from one machine to another, and
 168 .Fn getw
 169 is not recommended for portable applications.
 170 .Pp