changing the delimiter for cin (c++)

It is possible to change the inter-word delimiter for cin or any other std::istream, using std::ios_base::imbue to add a custom ctype facet.

If you are reading a file in the style of /etc/passwd, the following program will read each :-delimited word separately.

#include <locale>
#include <iostream>


struct colon_is_space : std::ctype<char> {
  colon_is_space() : std::ctype<char>(get_table()) {}
  static mask const* get_table()
  {
    static mask rc[table_size];
    rc[':'] = std::ctype_base::space;
    rc['\n'] = std::ctype_base::space;
    return &rc[0];
  }
};

int main() {
  using std::string;
  using std::cin;
  using std::locale;

  cin.imbue(locale(cin.getloc(), new colon_is_space));

  string word;
  while(cin >> word) {
    std::cout << word << "\n";
  }
}