std::ctype <char> :: scan_is

Locates the first character in the character array [ beg , end ) that satisfies the classification mask m , that is, the first character c such that table ( ) [ ( unsigned char ) c ] & m would return true .

If ( unsigned char ) c >= std:: ctype < char > :: table_size , then an implementation-defined value is substituted instead of table ( ) [ ( unsigned char ) c ] , possibly different for different values of c .

Parameters

Return value

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

Notes

Unlike the primary template std:: ctype , this specialization does not perform a virtual function call when classifying characters. To customize the behavior, a derived class may provide a non-default classification table to the base class constructor.

Example

#include <iostream>
#include <iterator>
#include <locale>
 
int main()
{
    std::locale loc("");
    auto& f = std::use_facet<std::ctype<char>>(loc);
 
    // skip until the first letter
    char s1[] = "      \t\t\n  Test";
    const char* p1 = f.scan_is(std::ctype_base::alpha, std::begin(s1), std::end(s1));
    std::cout << '\'' << p1 << "'\n";
 
    // skip until the first letter
    char s2[] = "123456789abcd";
    const char* p2 = f.scan_is(std::ctype_base::alpha, std::begin(s2), std::end(s2));
    std::cout << '\'' << p2 << "'\n";
}

'Test'
'abcd'

See also