custom separators, two ways

ctype.hpp

//  getting existing table for ctype<char> specialization
const auto temp = ctype<char>::classic_table();
//  create a copy of the table in vector container
vector<ctype<char>::mask> bar(temp, temp + ctype<char>::table_size);

//  add/remove stream separators using bitwise arithmetic.
//  use char-based indices because ascii codes here are equal to indices
bar[' '] ^= ctype_base::space;
bar['\t'] &= ~(ctype_base::space | ctype_base::cntrl);
bar[':'] |= ctype_base::space;
//  A ctype initialized with bar would delimit on '\n' and ':' but not ' ' or '\t'.

//  ....
//  usage of the mask above.
//  any istream here but we use cin as sample only.
//  do not forget to get raw memory area from vector by .data()
cin.imbue(locale(cin.getloc(), new ctype<char>(bar.data())));
//  to reset locale to default use this:
cin.imbue(locale(cin.getloc(), new ctype<char>));

//====================================================================
//  second way to customize delimiter symbols
//====================================================================
struct csv_whitespace : std::ctype<wchar_t>
{
    bool do_is(mask m, char_type c) const
    {
        if ((m & space) && c == L' ') {
            return false; // space will NOT be classified as whitespace
        }
        if ((m & space) && c == L',') {
            return true; // comma will be classified as whitespace
        }
        return ctype::do_is(m, c); // leave the rest to the parent class
    }
};
//  .....
cin.imbue(std::locale(cin.getloc(), new csv_whitespace));