1.\" $OpenBSD: tolower.3,v 1.11 2007/05/31 19:19:29 jmc 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.Dd $Mdocdate: May 31 2007 $ 35.Dt TOLOWER 3 36.Os 37.Sh NAME 38.Nm tolower , 39.Nm _tolower 40.Nd upper case to lower case letter conversion 41.Sh SYNOPSIS 42.Fd #include <ctype.h> 43.Ft int 44.Fn tolower "int c" 45.Ft int 46.Fn _tolower "int c" 47.Sh DESCRIPTION 48The 49.Fn tolower 50function converts an upper-case letter to the corresponding lower-case 51letter. 52The 53.Fn _tolower 54function is identical to 55.Fn tolower 56except that 57.Ar c 58must be an upper-case letter. 59.Sh RETURN VALUES 60If the argument to the 61.Fn tolower 62function is an upper-case letter, the corresponding lower-case letter 63is returned if there is one; otherwise the argument is returned unchanged. 64If the argument to the 65.Fn _tolower 66function is an upper-case letter, the corresponding lower-case letter 67is returned; otherwise the output is undefined. 68.\" In the 69.\" .Em ``C'' 70.\" locale, 71.\" .Fn tolower 72.\" maps only the characters for which 73.\" .Xr isupper 74.\" is true to the corresponding characters for which 75.\" .Xr islower 76.\" is true. 77.Sh SEE ALSO 78.Xr isalnum 3 , 79.Xr isalpha 3 , 80.Xr isascii 3 , 81.Xr isblank 3 , 82.Xr iscntrl 3 , 83.Xr isdigit 3 , 84.Xr isgraph 3 , 85.Xr islower 3 , 86.Xr isprint 3 , 87.Xr ispunct 3 , 88.Xr isspace 3 , 89.Xr isupper 3 , 90.Xr isxdigit 3 , 91.Xr stdio 3 , 92.Xr toascii 3 , 93.Xr toupper 3 , 94.Xr ascii 7 95.Sh STANDARDS 96The 97.Fn tolower 98and 99.Fn _tolower 100functions conform to 101.St -ansiC . 102