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.\" $FreeBSD$ 38.\" 39.Dd June 4, 1993 40.Dt TOLOWER 3 41.Os 42.Sh NAME 43.Nm tolower 44.Nd upper case to lower case letter conversion 45.Sh LIBRARY 46.Lb libc 47.Sh SYNOPSIS 48.Fd #include <ctype.h> 49.Ft int 50.Fn tolower "int c" 51.Sh DESCRIPTION 52The 53.Fn tolower 54function converts an upper-case letter to the corresponding lower-case 55letter. 56For single C 57.Va char Ns s 58locales (see 59.Xr multibyte 3 ) 60the value of the argument is 61representable as an 62.Li unsigned char 63or the value of 64.Dv EOF . 65.Sh RETURN VALUES 66If the argument is an upper-case letter, the 67.Fn tolower 68function returns the corresponding lower-case letter if there is 69one; otherwise the argument is returned unchanged. 70.Sh SEE ALSO 71.Xr isalnum 3 , 72.Xr isalpha 3 , 73.Xr isascii 3 , 74.Xr iscntrl 3 , 75.Xr isdigit 3 , 76.Xr isgraph 3 , 77.Xr islower 3 , 78.Xr isprint 3 , 79.Xr ispunct 3 , 80.Xr isspace 3 , 81.Xr isupper 3 , 82.Xr isxdigit 3 , 83.Xr multibyte 3 , 84.Xr stdio 3 , 85.Xr toascii 3 , 86.Xr toupper 3 , 87.Xr ascii 7 88.Sh STANDARDS 89The 90.Fn tolower 91function conforms to 92.St -ansiC . 93