1.\" $NetBSD: ctype.3,v 1.18 2008/04/17 16:24:40 apb Exp $ 2.\" 3.\" Copyright (c) 1991 Regents of the University of California. 4.\" All rights reserved. 5.\" 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)ctype.3 6.5 (Berkeley) 4/19/91 32.\" 33.Dd April 17, 2008 34.Dt CTYPE 3 35.Os 36.Sh NAME 37.Nm isalpha , 38.Nm isupper , 39.Nm islower , 40.Nm isdigit , 41.Nm isxdigit , 42.Nm isalnum , 43.Nm isspace , 44.Nm ispunct , 45.Nm isprint , 46.Nm isgraph , 47.Nm iscntrl , 48.Nm isblank , 49.Nm toupper , 50.Nm tolower , 51.Nd character classification and mapping functions 52.Sh LIBRARY 53.Lb libc 54.Sh SYNOPSIS 55.In ctype.h 56.Fa int c 57.br 58.Fn isalpha c 59.Fn isupper c 60.Fn islower c 61.Fn isdigit c 62.Fn isxdigit c 63.Fn isalnum c 64.Fn isspace c 65.Fn ispunct c 66.Fn isprint c 67.Fn isgraph c 68.Fn iscntrl c 69.Fn isblank c 70.Fn toupper c 71.Fn tolower c 72.Sh DESCRIPTION 73The above functions perform character tests and conversions on the integer 74.Ar c . 75.Pp 76See the specific manual pages for information about the 77test or conversion performed by each function. 78.Sh EXAMPLES 79To print an upper-case version of a string on stdout, use the following 80code: 81.Bd -literal 82const char *s = ...; 83while (*s != '\\0') { 84 putchar(toupper((int)(unsigned char)*s)); 85 s++; 86} 87.Ed 88.Sh SEE ALSO 89.Xr isalnum 3 , 90.Xr isalpha 3 , 91.Xr isblank 3 , 92.Xr iscntrl 3 , 93.Xr isdigit 3 , 94.Xr isgraph 3 , 95.Xr islower 3 , 96.Xr isprint 3 , 97.Xr ispunct 3 , 98.Xr isspace 3 , 99.Xr isupper 3 , 100.Xr isxdigit 3 , 101.Xr tolower 3 , 102.Xr toupper 3 , 103.Xr ascii 7 104.Sh STANDARDS 105These functions, with the exception of 106.Fn isblank , 107conform to 108.St -ansiC . 109.Sh CAVEATS 110The first argument of these functions is of type 111.Vt int , 112but only a very restricted subset of values are actually valid. 113The argument must either be the value of the macro 114.Dv EOF 115(which has a negative value), 116or must be a non-negative value within the range representable as 117.Vt unsigned char . 118Passing invalid values leads to undefined behavior. 119.Pp 120Values of type 121.Vt int 122that were returned by 123.Xr getc 3 , 124.Xr fgetc 3 , 125and similar functions or macros 126are already in the correct range, and may be safely passed to these 127.Nm ctype 128functions without any casts. 129.Pp 130Values of type 131.Vt char 132or 133.Vt signed char 134must first be cast to 135.Vt unsigned char , 136to ensure that the values are within the correct range. 137The result should then be cast to 138.Vt int 139to avoid warnings from some compilers. 140Casting a negative-valued 141.Vt char 142or 143.Vt signed char 144directly to 145.Vt int 146will produce a negative-valued 147.Vt int , 148which will be outside the range of allowed values 149(unless it happens to be equal to 150.Dv EOF , 151but even that would not give the desired result). 152