Re: How to avoid CMapStringToPtr sorting ?

"Giovanni Dicanio" <>
Thu, 25 Oct 2007 10:56:44 +0200
"Abin" <> ha scritto nel messaggio

CMapStringToOb m_myMap;

POSITION pPos = m_myMap.GetStartPosition();
CString strName;
CObject *pObj;
while (pPos != NULL)
m_myMap.GetNextAssoc(pPos, strName, pObj);
When i iterate the keys i get "ZEE", "ABB" followed by "CCC".

Is there any way to retrieve the keys in same order of insertion.

For what I know: no, if you only use map.

I think you should use both a map and a vector (or linked list). The map
stores the association string key -> ptr, and the vector stores information
about key insertion order.

So, when you add a new key to the map, you also add this key to the vector.
And you retrieve the keys in insertion order, looping for each vector item.

(This is what I suggested in the above post.)

This is a sample code, to show what I mean (I'm sorry, but I prefer using
STL containers like std::vector and std::map and not MFC containers - also
note that STL containers work well with CString, which is a well-designed
string class for Windows development, better than std::string/wstring,


void CTestOrderMapDlg::OnBnClickedRunTest()
    typedef std::vector< CString > StringList;
    typedef std::map< CString, Person * > Persons;

    StringList names;
    Persons persons;

    // Add some objects to the collection (map).
    // Also add the key to the key list, so we can retrieve
    // that in the same order of insertion.

    persons[ _T("Bob") ] = new Person( _T("Bob"), 40 );
    names.push_back( _T("Bob" ) );

    persons[ _T("Mike") ] = new Person( _T("Mike"), 70 );
    names.push_back( _T("Mike" ) );

    persons[ _T("Jeff") ] = new Person( _T("Jeff"), 28 );
    names.push_back( _T("Jeff" ) );

    // Print content in insertion order
    StringList::const_iterator it;
    for ( it = names.begin(); it != names.end(); ++it )
        WriteLine( persons[ *it ]->ToString() );

    // Clear objects
    for ( it = names.begin(); it != names.end(); ++it )
        Person * person = persons[ *it ];
        delete person;
        persons[ *it ] = NULL;


These are the other code blocks required by the above code (m_lstOutput is a


// Test class to be stored in the map
class Person
        : Age(0)

    explicit Person( LPCTSTR name, int age )
        : Name( name ), Age( age )

    CString ToString() const
        CString s;
        s.Format( _T("%s (%d years old)"), Name, Age );
        return s;

    CString Name;
    int Age;

// Clear the output list-box
void CTestOrderMapDlg::Clear()

// Add a new line to the output list-box
void CTestOrderMapDlg::WriteLine( LPCTSTR line )
    ASSERT( line != NULL );
    m_lstOutput.AddString( line );



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