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Use an API Function to Limit the Entry of a Textbox Control

First, place the function ischaralpha in the proyect. In this example it’s in the general declarations section of the form:

Private Declare Function IsCharAlpha Lib "user32" Alias "IsCharAlphaA"(ByVal cChar As Byte) As Long

Next, place a textbox in the form. Then, copy the next code to limit the user entry only to alphabeticcharacters:

If KeyAscii = vbKeyBack Or KeyAscii = vbKeySpace ThenKeyAscii = KeyAsciiExit SubEnd Ifnum = IsCharAlpha(KeyAscii)If num = 0 ThenKeyAscii = 0End If

With some changes in the code, you can limit the user entry to only numbers:

permitir solo numerosIf KeyAscii = vbKeyBack Or KeyAscii = vbKeySpace ThenKeyAscii = KeyAsciiExit SubEnd IfSelect Case Chr(KeyAscii)Case "0", "1", "2", "3", "4", "5", "6", "7", "8", "9"KeyAscii = KeyAsciiCase ElseKeyAscii = 0End Select

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