Limiting Characters in Edit Box :: MFC

This is a discussion on Limiting Characters in Edit Box :: MFC within the Windows Programming forums, part of the Platform Specific Boards category; Hi. I would like to limit the number of characters a user make enter at any given time to a ...

  1. #1
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    Limiting Characters in Edit Box :: MFC

    Hi.

    I would like to limit the number of characters a user make enter at any given time to a finite integer. For example, let say I have an edit box in a dialog box for entering zip code. I would like to limit the number of characters to *exactly five*.

    I have tried using DDV verification feature in a dialog box. However, I found that the user can overflow the edit box. For example:

    limit: 500
    User: 500000

    If the user overflow the edit box, for DDV will consider the data entered as being valid. I believe the problem has something to do with overflowing a datatype.

    Nonetheless, what is the best way to limit the number of characters/digits entered in an edit box?

    Thanks,
    Kuphryn

  2. #2
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    In your message routine, you could try:
    Code:
    case EDIT_ID_BLAH:
    if (strlen(zipcode) == 5) // zipcode is variable which holds zip code
    {
    break;
    }
    break;
    Or something like that. It might give you some ideas. Or maybe this:
    Code:
    case EDIT_ID_BLAH:
    if (strlen(zipcode) == 5) // zipcode is variable which holds zip code
    {
    GetDlgItemText(.....); // get contents of edit box
    SetDlgItemText(....); // disallow anymore than 5 chars/nums whatever
    break;
    }
    break;
    Not sure about that either but yo!!

  3. #3
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    Okay. Thanks.

    Kuphryn

  4. #4
    &TH of undefined behavior Fordy's Avatar
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    There is a EM_SETLIMITTEXT message that you can send to an edit....try that.

  5. #5
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    Okay.

    The solution is to use a CString variable holding the value of the edit box. I am referring to the example of the five digit zip code. For example, lets consider that the variable is an int. If the variable is declared as an int, there will be an overflow if the user enters 99999999999999. The solution I came up with is to define it as a CString. Here is the verification part.

    -----
    void CMyDlg::OnEnChangeMyEditBox()
    {
    UpdateData(TRUE);


    // the length must be exactly five
    // the value must be between 10000 and 91000

    if (m_EditPortListen.GetLength() == 5 &&
    atoi(static_cast<LPCTSTR>(m_MyEditBox)) >= 10000 &&
    atoi(static_cast<LPCTSTR>(m_MyEditBox)) <= 91000)
    SetModified(TRUE);

    else
    {
    m_MyEditBox.Format("%d", 10000);
    UpdateData(FALSE);
    SetModified(FALSE);
    }
    }
    -----

    The code above works well.

    Kuphryn

  6. #6
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    try giving this limitation:
    min: 10000
    max: 99999
    tudehopet uses Borland Compiler 5.5
    and Visual C++ 6.

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