1.\" $NetBSD: ctype.3,v 1.19 2009/03/11 12:57:03 joerg 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 March 11, 2009 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.Fn isalpha "int c" 57.Fn isupper "int c" 58.Fn islower "int c" 59.Fn isdigit "int c" 60.Fn isxdigit "int c" 61.Fn isalnum "int c" 62.Fn isspace "int c" 63.Fn ispunct "int c" 64.Fn isprint "int c" 65.Fn isgraph "int c" 66.Fn iscntrl "int c" 67.Fn isblank "int c" 68.Fn toupper "int c" 69.Fn tolower "int c" 70.Sh DESCRIPTION 71The above functions perform character tests and conversions on the integer 72.Ar c . 73.Pp 74See the specific manual pages for information about the 75test or conversion performed by each function. 76.Sh EXAMPLES 77To print an upper-case version of a string on stdout, use the following 78code: 79.Bd -literal 80const char *s = ...; 81while (*s != '\\0') { 82 putchar(toupper((int)(unsigned char)*s)); 83 s++; 84} 85.Ed 86.Sh SEE ALSO 87.Xr isalnum 3 , 88.Xr isalpha 3 , 89.Xr isblank 3 , 90.Xr iscntrl 3 , 91.Xr isdigit 3 , 92.Xr isgraph 3 , 93.Xr islower 3 , 94.Xr isprint 3 , 95.Xr ispunct 3 , 96.Xr isspace 3 , 97.Xr isupper 3 , 98.Xr isxdigit 3 , 99.Xr tolower 3 , 100.Xr toupper 3 , 101.Xr ascii 7 102.Sh STANDARDS 103These functions, with the exception of 104.Fn isblank , 105conform to 106.St -ansiC . 107.Sh CAVEATS 108The first argument of these functions is of type 109.Vt int , 110but only a very restricted subset of values are actually valid. 111The argument must either be the value of the macro 112.Dv EOF 113(which has a negative value), 114or must be a non-negative value within the range representable as 115.Vt unsigned char . 116Passing invalid values leads to undefined behavior. 117.Pp 118Values of type 119.Vt int 120that were returned by 121.Xr getc 3 , 122.Xr fgetc 3 , 123and similar functions or macros 124are already in the correct range, and may be safely passed to these 125.Nm ctype 126functions without any casts. 127.Pp 128Values of type 129.Vt char 130or 131.Vt signed char 132must first be cast to 133.Vt unsigned char , 134to ensure that the values are within the correct range. 135The result should then be cast to 136.Vt int 137to avoid warnings from some compilers. 138Casting a negative-valued 139.Vt char 140or 141.Vt signed char 142directly to 143.Vt int 144will produce a negative-valued 145.Vt int , 146which will be outside the range of allowed values 147(unless it happens to be equal to 148.Dv EOF , 149but even that would not give the desired result). 150