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std::isalnum

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< cpp‎ | string‎ | byte
Revision as of 15:14, 6 July 2013 by P12 (Talk | contribs)

Defined in header <cctype>
int isalnum( int ch );

Checks if the given character is an alphanumeric character as classified by the current C locale. In the default locale, the following characters are alphanumeric:

  • digits (0123456789)
  • uppercase letters (ABCDEFGHIJKLMNOPQRSTUVWXYZ)
  • lowercase letters (abcdefghijklmnopqrstuvwxyz)

Contents

Parameters

ch - character

Return value

Non-zero value (true) if the character is an alphanumeric character, 0 (false) otherwise.

Example

Demonstrates the use of isalnum() with different locales (OS-specific).

#include <iostream>
#include <cctype>
#include <clocale>
 
int main()
{
    const char c = '\xdf'; // German letter ß in ISO-8859-1
 
    std::cout << "isalnum(\'\\xdf\', default C locale) returned "
               << std::boolalpha << (bool)std::isalnum(c) << '\n';
 
    std::setlocale(LC_ALL, "de_DE.iso88591");
    std::cout << "isalnum(\'\\xdf\', ISO-8859-1 locale) returned "
              << std::boolalpha << (bool)std::isalnum(c) << '\n';
 
}

Output:

isalnum('\xdf', default C locale) returned false
isalnum('\xdf', ISO-8859-1 locale) returned true

See also

checks if a character is classified as alphanumeric by a locale
(function template) [edit]
checks if a wide character is alphanumeric
(function) [edit]
C documentation for isalnum
ASCII values
(hex)
characters

iscntrl
iswcntrl

isprint
iswprint

isspace
iswspace

isblank
iswblank

isgraph
iswgraph

ispunct
iswpunct

isalnum
iswalnum

isalpha
iswalpha

isupper
iswupper

islower
iswlower

isdigit
iswdigit

isxdigit
iswxdigit

0 - 8 0x00-0x08 control codes (NUL, etc.) ≠0 0 0 0 0 0 0 0 0 0 0 0
9 0x09 tab (\t) ≠0 0 ≠0 ≠0 0 0 0 0 0 0 0 0
10 - 13 0x0A-0x0D whitespaces (\n,\v,\f,\r) ≠0 0 ≠0 0 0 0 0 0 0 0 0 0
14 - 31 0x0E-0x1F control codes ≠0 0 0 0 0 0 0 0 0 0 0 0
32 0x20 space 0 ≠0 ≠0 ≠0 0 0 0 0 0 0 0 0
33 - 47 0x21-0x2F !"#$%&'()*+,-./ 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0
48 - 57 0x30-0x39 0123456789 0 ≠0 0 0 ≠0 0 ≠0 0 0 0 ≠0 ≠0
58 - 64 0x3a-0x40 :;<=>?@ 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0
65 - 70 0x41-0x46 ABCDEF 0 ≠0 0 0 ≠0 0 ≠0 ≠0 ≠0 0 0 ≠0
71 - 90 0x47-0x5A GHIJKLMNOPQRSTUVWXYZ 0 ≠0 0 0 ≠0 0 ≠0 ≠0 ≠0 0 0 0
91 - 96 0x5B-0x60 [\]^_` 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0
97 -102 0x61-0x66 abcdef 0 ≠0 0 0 ≠0 0 ≠0 ≠0 0 ≠0 0 ≠0
103-122 0x67-0x7A ghijklmnopqrstuvwxyz 0 ≠0 0 0 ≠0 0 ≠0 ≠0 0 ≠0 0 0
123-126 0x7B-0x7E {|}~ 0 ≠0 0 0 ≠0 ≠0 0 0 0 0 0 0
127 0x7F backspace character (DEL) ≠0 0 0 0 0 0 0 0 0 0 0 0