Re: Simple Edit Box Validation???

From:

David Lowndes <DavidL@example.invalid>

Newsgroups:

microsoft.public.vc.mfc

Date:

Wed, 27 Jun 2007 00:45:03 +0100

Message-ID:

<qv83839se922v45a0rn5fopl8dcbgg8b46@4ax.com>

I need to create some simple TextBox validation. I will need
to limit the length to a fixed number of characters.

CEdit::SetLimitText (EM_SETLIMITTEXT)

I also
need to restrict the data entered two different ways:
(a) Numeric Only
(b) AlphaBetic or Numeric Only (hexadecimal numbers), with
conversion to uppercase.

Here's an example of a derived edit control class that handles the
EN_UPDATE notification message. The EN_UPDATE message is useful to
handle as it caters for both normal entry and clipboard paste
operations.

void CHexEdit::OnUpdate()
{
    CString str;

    GetWindowText( str );

    /* Access the string buffer directly */
    LPSTR pBuff = str.GetBuffer( 10 );

    bool bProblem = false;

    for ( int indx = 0; indx < str.GetLength(); indx++ )
    {
        char nChar = pBuff[indx];

        if ( ( ( nChar >= '0' ) && ( nChar <= '9') ) ||
            ( ( nChar >= 'A' ) && ( nChar <= 'F' ) ) ||
            ( ( nChar >= 'a' ) && ( nChar <= 'f' ) ) )
        {
        }
        else
        {
            bProblem = true;
            break;
        }
    }

    str.ReleaseBuffer();

    if ( bProblem )
    {
        int start, end;

        /* Find the current caret position */
        GetSel( start, end );

        /* Restore the last good text that was entered */
        SetWindowText( m_LastGood );

        /* Restore the caret */
        SetSel( start-1, end-1, true );

        /* Let the user know */
        MessageBeep( MB_OK );
    }
    else
    {
        /* Store the last good entry string in a
         * member variable of the Hex edit class
         */
        m_LastGood = str;
    }
}

Dave