1.\" $NetBSD: tolower.3,v 1.14 2008/04/17 16:25:36 apb Exp $ 2.\" 3.\" Copyright (c) 1989, 1991 The Regents of the University of California. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" the American National Standards Committee X3, on Information 8.\" Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)tolower.3 5.2 (Berkeley) 6/29/91 35.\" 36.Dd April 17, 2008 37.Dt TOLOWER 3 38.Os 39.Sh NAME 40.Nm tolower 41.Nd upper case to lower case letter conversion 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In ctype.h 46.Ft int 47.Fn tolower "int c" 48.Sh DESCRIPTION 49The 50.Fn tolower 51function converts an upper-case letter to the corresponding lower-case 52letter. 53.Sh RETURN VALUES 54If the argument is an upper-case letter, the 55.Fn tolower 56function returns the corresponding lower-case letter if there is 57one; otherwise the argument is returned unchanged. 58.\" In the 59.\" .Em ``C'' 60.\" locale, 61.\" .Fn tolower 62.\" maps only the characters for which 63.\" .Xr isupper 64.\" is true to the corresponding characters for which 65.\" .Xr islower 66.\" is true. 67.Sh SEE ALSO 68.Xr ctype 3 , 69.Xr isalnum 3 , 70.Xr isalpha 3 , 71.Xr isascii 3 , 72.Xr iscntrl 3 , 73.Xr isdigit 3 , 74.Xr isgraph 3 , 75.Xr islower 3 , 76.Xr isprint 3 , 77.Xr ispunct 3 , 78.Xr isspace 3 , 79.Xr isupper 3 , 80.Xr isxdigit 3 , 81.Xr stdio 3 , 82.Xr toascii 3 , 83.Xr toupper 3 , 84.Xr ascii 7 85.Sh STANDARDS 86The 87.Fn tolower 88function conforms to 89.St -ansiC . 90.Sh CAVEATS 91The argument to 92.Fn tolower 93must be 94.Dv EOF 95or representable as an 96.Vt unsigned char ; 97otherwise, the behavior is undefined. 98See the 99.Sx CAVEATS 100section of 101.Xr ctype 3 102for more details. 103