NAME¶

std::isxdigit(std::locale) - std::isxdigit(std::locale)

Synopsis¶

Defined in header <locale>
template< class CharT >
bool isxdigit( CharT ch, const locale& loc );

Checks if the given character is classified as a hexadecimal digit by the given
locale's std::ctype facet.

Parameters¶

ch - character
loc - locale

Return value¶

Returns true if the character is classified as a hexadecimal digit, false otherwise.

Possible implementation¶

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

Example¶

// Run this code

#include <iostream>
#include <locale>
#include <string>
#include <unordered_set>

struct gxdigit_ctype : std::ctype<wchar_t>
{
std::unordered_set<wchar_t> greek_digits{L'α', L'β', L'γ', L'δ', L'ε', L'ζ'};

bool do_is(mask m, char_type c) const override
{
return (m & xdigit) && greek_digits.contains(c)
? true // 6 first Greek small letters will be classified as digits
: ctype::do_is(m, c); // leave the rest to the parent class
}
};

int main()
{
std::wstring text = L"0123456789abcdefABCDEFαβγδεζηθικλμ";
std::locale loc(std::locale(""), new gxdigit_ctype);

std::locale::global(std::locale("en_US.utf8"));
std::wcout.imbue(std::locale());

std::wcout << "Hexadecimal digits in text: ";
for (const wchar_t c : text)
if (std::isxdigit(c, loc))
std::wcout << c << L' ';
std::wcout << L'\n';

std::wcout << "Not hexadecimal digits in text: ";
for (const wchar_t c : text)
if (not std::isxdigit(c, loc))
std::wcout << c << L' ';
std::wcout << L'\n';
}

Output:¶

Hexadecimal digits in text: 0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F α β γ δ ε ζ
Not hexadecimal digits in text: η θ ι κ λ μ

See also¶

isxdigit checks if a character is a hexadecimal character
(function)
iswxdigit checks if a wide character is a hexadecimal character
(function)