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| Title | See if a string contains only digits or only letters |
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| Keywords | string, numeric, alpha, digits, letters |
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| Categories | Strings |
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This example uses two functions, AllDigits and AllLetters, that return True if a string contains only digits/letters. They examine each character to see if they fall within the allowed range.
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' Return True if the string contains only digits.
Private Function AllDigits(ByVal txt As String) As Boolean
Dim ch As String
Dim i As Integer
AllDigits = True
For i = 1 To Len(txt)
' See if the next character is a non-digit.
ch = Mid$(txt, i, 1)
If ch < "0" Or ch > "9" Then
' This is not a digit.
AllDigits = False
Exit For
End If
Next i
End Function
' Return True if the string contains only letters.
Private Function AllLetters(ByVal txt As String) As Boolean
Dim ch As String
Dim i As Integer
AllLetters = True
txt = UCase$(txt)
For i = 1 To Len(txt)
' See if the next character is a non-digit.
ch = Mid$(txt, i, 1)
If ch < "A" Or ch > "Z" Then
' This is not a letter.
AllLetters = False
Exit For
End If
Next i
End Function
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Formatted by
Neil Crosby
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