Detecting mixed case strings in ASP Classic

I needed to detect a mixed case string in classic ASP. I define a mixed case string as containing both upper and lower case characters, like AuxagGsrLpa. I could not find a free function on the web to make this decision, so I wrote one.

<%
	Function isMixedCase( str )
		'detects mixed case strings using the english alphabet
		'ignores spaces and other non-alphabetic characters
		str = trim( str )
		isMixed = false
		lastCase = ""
		for i=1 to len( str )
			currentChar = mid( str, i, 1 )
			if asc( currentChar ) >= 65 and asc( currentChar ) <= 90 then
				if lastCase <> "" and lastCase <> "upper" then
					isMixed = true
					exit for
				else
					lastCase = "upper"
				end if
			else
				if asc( currentChar ) >= 97 and asc( currentChar ) <= 122 then
					'lower
					if lastCase <> "" and lastCase <> "lower" then
						isMixed = true
						exit for
					else
						lastCase = "lower"
					end if
				else
					lastCase = ""
				end if
			end if
		next
		if isMixed then
			isMixedCase = true
		else
			isMixedCase = false
		end if
	End Function
%>

Here are a few test strings to demonstrate the functionality:


<% response.write "Hello " & isMixedCase( "Hello " ) & " <br>" response.write "hello! " & isMixedCase( "hello!" ) & " <br>" response.write "HELLO " & isMixedCase( "HELLO " ) & " <br>" response.write "hello there " & isMixedCase( "hello there" ) & " <br>" response.write "hellothere " & isMixedCase( "hellothere" ) & " <br>" response.write "hellotherE " & isMixedCase( "hellotherE" ) & " <br>" %>

Here is the resulting HTML output of the tests:

Hello True
hello! False
HELLO False
hello there False
hellothere False
hellotherE True