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.\" %sccs.include.redist.man% 9.\" 10.\" @(#)tolower.3 8.1 (Berkeley) 06/04/93 11.\" 12.Dd 13.Dt TOLOWER 3 14.Os 15.Sh NAME 16.Nm tolower 17.Nd upper case to lower case letter conversion 18.Sh SYNOPSIS 19.Fd #include <ctype.h> 20.Ft int 21.Fn tolower "int c" 22.Sh DESCRIPTION 23The 24.Fn tolower 25function converts an upper-case letter to the corresponding lower-case 26letter. 27.Sh RETURN VALUES 28If the argument is an upper-case letter, the 29.Fn tolower 30function returns the corresponding lower-case letter if there is 31one; otherwise the argument is returned unchanged. 32.\" In the 33.\" .Em ``C'' 34.\" locale, 35.\" .Fn tolower 36.\" maps only the characters for which 37.\" .Xr isupper 38.\" is true to the corresponding characters for which 39.\" .Xr islower 40.\" is true. 41.Sh SEE ALSO 42.Xr isascii 3 , 43.Xr isalnum 3 , 44.Xr isalpha 3 , 45.Xr iscntrl 3 , 46.Xr isdigit 3 , 47.Xr isgraph 3 , 48.Xr islower 3 , 49.Xr isprint 3 , 50.Xr ispunct 3 , 51.Xr isspace 3 , 52.Xr isupper 3 , 53.Xr isxdigit 3 , 54.Xr toascii 3 , 55.Xr toupper 3 , 56.Xr stdio 3 57.Xr ascii 7 58.Sh STANDARDS 59The 60.Fn tolower 61function conforms to 62.St -ansiC . 63