NAME¶

std::ctype::scan_is,std::ctype::do_scan_is - std::ctype::scan_is,std::ctype::do_scan_is

Synopsis¶

Defined in header <locale>
public: (1)
const CharT* scan_is( mask m, const CharT* beg, const CharT* end ) const;
protected:
virtual const CharT* do_scan_is( mask m, const CharT* beg, const CharT* end ) (2)
const;

1) Public member function, calls the protected virtual member function do_scan_is of
the most derived class.
2) Locates the first character in the character array [beg, end) that satisfies the
classification mask m, that is, the first character c such that is(m, c) would
return true.

Parameters¶

m - mask to search for
beg - pointer to the first character in an array of characters to search
end - one past the end pointer for the array of characters to search

Return value¶

Pointer to the first character in [beg, end) that satisfies the mask, or end if no
such character was found.

Example¶

// Run this code

#include <clocale>
#include <iostream>
#include <iterator>
#include <locale>

int main()
{
std::setlocale(LC_ALL, "en_US.utf8");
std::wcout.imbue(std::locale("en_US.utf8"));
auto& f = std::use_facet<std::ctype<wchar_t>>(std::wcout.getloc());

// skip until the first letter
wchar_t s1[] = L" \t\t\n Кошка";
const wchar_t* p1 = f.scan_is(std::ctype_base::alpha, std::begin(s1), std::end(s1));
std::wcout << '\'' << p1 << "'\n";

// skip until the first letter
wchar_t s2[] = L"123456789ネプネプ";
const wchar_t* p2 = f.scan_is(std::ctype_base::alpha, std::begin(s2), std::end(s2));
std::wcout << '\'' << p2 << "'\n";
}

Output:¶

'Кошка'
'ネプネプ'

Defect reports

The following behavior-changing defect reports were applied retroactively to
previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 152 C++98 the effect of do_scan_is mentioned is(m), corrected to is(m, c)
but is does not have such an overload

See also¶

locates the first character in a sequence that conforms to given
scan_is classification, using the classification table
(public member function of std::ctype<char>)
do_scan_not locates the first character in a sequence that fails given
[virtual] classification
(virtual protected member function)