Simple combo box questions - Xtreme Visual Basic Talk

05-23-2005, 01:11 AM

cheung

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Join Date: Jun 2004

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Simple combo box questions

Hi,

i have the following simple combo box questions:
1. how can I limit the max length of the input?
2. how can I prevent the user from overtyping the values in the list?

Regards,
Cheung

05-23-2005, 01:23 AM

Marathon Man Marathon Man is offline

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1. Check the length of the .Text property on _KeyDown
2. Change the .Style to vbComboDropDownList (2)

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05-23-2005, 01:34 PM

Lar_19

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Another way to simulate a 'MaxLength' property in a combobox would be to set it using the API. Here is an example for you...

Code:

Option Explicit

Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" ( _
                                ByVal hwnd As Long, ByVal wMsg As Long, _
                                ByVal wParam As Long, lParam As Any) As Long
Const CB_LIMITTEXT = &H141

Private Sub Form_Load()
' Pass the maximum number of characters in the wParam of the SendMessage() API
' function. In this example the length will be limited to ten characters.
   Call SendMessage(Combo1.hwnd, CB_LIMITTEXT, 10, ByVal 0&)
End Sub

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05-24-2005, 12:04 AM

Marathon Man Marathon Man is offline

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Neat.

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05-24-2005, 12:13 AM

sindhuKV

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Posts: 380

ya cool solution.
it would have been tough to toggle between
KeyDown/Keypress and Style property(DropDownList)

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05-24-2005, 01:29 PM

Lar_19

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Location: Vancouver, USA

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Also I should have mentioned that you can remove the restrictions on the length at run-time by making another call and passing zero as the character limit. I found that useful in an app where I wanted to reuse the same combo for multiple purposes with varying requirements for the max length, including no restrictions at all. Basically I just wrote a function that incorporated the call to SendMessage and passed in the combo along with the number of characters needed as it's parameters.
Hope you find this tip useful.

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