newkey.hpp

stl自带源码

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
namespace MyLib {
    template <class Cont>
    inline
    bool replace_key (Cont& c,
                      const typename Cont::key_type& old_key,
                      const typename Cont::key_type& new_key)
    {
        typename Cont::iterator pos;
        pos = c.find(old_key);
        if (pos != c.end()) {
            // insert new element with value of old element
            c.insert(typename Cont::value_type(new_key,
                                               pos->second));
            // remove old element
            c.erase(pos);
            return true;
        }
        else {
            // key not found
            return false;
        }
    }
}