how to search a string character by character

Hi everyone,

Need to be able to search a string and compare each character to a list of valid characters.

example:
string1="vb-programming"
string2="vb=programming"
valid characters are a-z, A-Z, 0-9, _, -, .

this would find all these characters valid in string1 to be valid and find "=" in string2 to be invalid thus making that string an invalid string

any help or direction would be appreciated

btw i have been trying to use instr functions to accomplish this and have only been able to search
for "1" character at a time :(

thx harold

sorry but the category should not be activex, should be controls or misc

public Function ValidString(byval sInput as string) as Boolean

Dim iLen as Integer
Dim iCtr as Integer
Dim sChar as string

iLen = len(sInput)
for iCtr = 1 to iLen
sChar = mid(sInput, iCtr, 1)
If Not sChar Like "[0-9A-Za-z_]" And sChar <> "-" then Exit Function
next
ValidString = true

End Function