# std::ctype<CharT>::scan_is, std::ctype<CharT>::do_scan_is

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< cpp‎ | locale‎ | ctype

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

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

    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), but `is` does not have such an overload | corrected to is(m, c)

### See also

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

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