std::isdigit(std::locale)

Defined in header <locale>

template< class charT >
bool isdigit( charT ch, const locale& loc );

Checks if the given character is classified as a 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 digit, false otherwise.

Possible implementation

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

Example

#include <iostream>
#include <locale>
#include <string>
#include <set>
  
struct jdigit_ctype : std::ctype<wchar_t>
{
    std::set<wchar_t> jdigits{L'一',L'二',L'三',L'四',L'五',L'六',L'七',L'八',L'九',L'十'};
    bool do_is(mask m, char_type c) const {
        if ((m & digit) && jdigits.count(c))
            return true; // Japanese digits will be classified as digits
        return ctype::do_is(m, c); // leave the rest to the parent class
    }
};
  
int main()
{
  
    std::wstring text = L"123一二三１２３";
    std::locale loc(std::locale(""), new jdigit_ctype);
  
    std::locale::global(std::locale(""));
    std::wcout.imbue(std::locale());
  
    for(wchar_t c : text)
        if(std::isdigit(c, loc))
            std::wcout << c << " is a digit\n";
        else
            std::wcout << c << " is NOT a digit\n";
}

Output:

1 is a digit
2 is a digit
3 is a digit
一 is a digit
二 is a digit
三 is a digit
１ is NOT a digit
２ is NOT a digit
３ is NOT a digit

isdigit	checks if a character is a digit (function)
iswdigit	checks if a wide character is a digit (function)

std::isdigit(std::locale)

Parameters

Return value

Possible implementation

Example

See also