Re: CMAP under vs2005+

"Tommy" <tommy767@gmail.com> ha scritto nel messaggio
news:%23XGVnJLNJHA.5060@TK2MSFTNGP02.phx.gbl...


[...]


Hi,

I learned that MFC CMap class is not very good, I would suggest you to use
std::map.
Note that you can mix std::map with CString class (from MFC/ATL).

So, if you want a case insensitive map from string to string, using CString
class for strings, and std::map for mapping, you may consider providing a
custom key comparer for std::map.

The custom key comparer is responsible to do the case *in*sensitive
comparison. For that purpose, CString offers a CompareNoCase() method, that
you can use.

CString::CompareNoCase()
http://msdn.microsoft.com/en-us/library/aa314315.aspx

The custom comparer is a class with a public method overloading operator(),
in this form:

  bool operator()( const CString & left, const CString & right ) const;

It is a predicate, that returns true if 'left < right'; of course, inside
the implementation of this operator(), you can define your own custom
comparison relation, in this case using CString::CompareNoCase():

<code>

struct CaseInsensitiveStringComparer
{
    // functor for operator <
    bool operator()(const CString & left, const CString & right) const
    {
        // Case insensitive comparison
        return ( left.CompareNoCase( right ) < 0 );
    }
};

</code>

You can pass this custom comparer as third template parameter of std::map
(the first template parameter is the key type, the second template parameter
is the "destination" value type):

<code>

//
// Map string --> string, using case insensitive comparison of string keys
//
typedef std::map< CString, CString, CaseInsensitiveStringComparer >
StringDictionaryCaseInsensitive;

</code>

You can test like this (#include <map> for std::map class)

<code>

StringDictionaryCaseInsensitive test;
test[ _T("Bob") ] = _T("123");
test[ _T("Jeff") ] = _T("456");
test[ _T("BOB") ] = _T("000"); // override first Bob

ASSERT( test[ _T("Bob") ] == _T("000") );

</code>

HTH,
Giovanni