1.\" Copyright (c) 1989, 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.\" the American National Standards Committee X3, on Information 6.\" 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.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" @(#)tolower.3 8.1 (Berkeley) 6/4/93 37.\" 38.Dd June 4, 1993 39.Dt TOLOWER 3 40.Os 41.Sh NAME 42.Nm tolower 43.Nd upper case to lower case letter conversion 44.Sh SYNOPSIS 45.Fd #include <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 isascii 3 , 69.Xr isalnum 3 , 70.Xr isalpha 3 , 71.Xr iscntrl 3 , 72.Xr isdigit 3 , 73.Xr isgraph 3 , 74.Xr islower 3 , 75.Xr isprint 3 , 76.Xr ispunct 3 , 77.Xr isspace 3 , 78.Xr isupper 3 , 79.Xr isxdigit 3 , 80.Xr toascii 3 , 81.Xr toupper 3 , 82.Xr stdio 3 , 83.Xr ascii 7 84.Sh STANDARDS 85The 86.Fn tolower 87function conforms to 88.St -ansiC . 89