Home Original page

std::isalnum(std::locale) - cppreference.com

From cppreference.com

template< class CharT > bool isalnum( CharT ch, const locale& loc );

Checks if the given character is 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