std::isalnum(std::locale)

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< cpp‎ | locale
 
 
Localizations library
Locales and facets
Locales
Facet category base classes
ctype facets
numeric facets
collate facets
time facets
monetary facets
messages facets
Character classification and conversion
Character classification
Conversions
(C++11/17*)
(C++11/17*)
Code conversion facets
(C++11/17*)
(C++11/17*)    
(C++11/17*)
C locale
 
Defined in header <locale>
template< class CharT >
bool isalnum( CharT ch, const locale& loc );

Checks if the given character classified as an alphanumeric character by the given locale's std::ctype facet.

Parameters

ch - character
loc - locale

Return value

Returns true if the character is classified as alphanumeric, false otherwise.

Possible implementation

template< class CharT >
bool isalnum( CharT ch, const std::locale& loc ) {
    return std::use_facet<std::ctype<CharT>>(loc).is(std::ctype_base::alnum, ch);
}

Example

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

#include <iostream>
#include <locale>
int main()
{
    const wchar_t c = L'\u2135'; // mathematical symbol aleph
 
    std::locale loc1("C");
    std::cout << "isalnum('ℵ', C locale) returned "
              << std::boolalpha << std::isalnum(c, loc1) << '\n';
 
    std::locale loc2("en_US.UTF-8");
    std::cout << "isalnum('ℵ', Unicode locale) returned "
              << std::boolalpha << std::isalnum(c, loc2) << '\n';
}

Possible output:

isalnum('ℵ', C locale) returned false
isalnum('ℵ', Unicode locale) returned true

See also

checks if a character is alphanumeric
(function)
checks if a wide character is alphanumeric
(function)