This is actually very hard to do, and tends to upset the users. In principle
you can use the KeyPress event to check what key is used and to prevent
those you don't want; but apart from digits you have to allow for backspace,
ctrl-C, ctrl-X, etc. Then if you allow ctrl-V you have to check that what is
pasted in is also acceptable ... Even the definition of 'numeric' is
problematic if you're working key-by-key. A decimal point is OK, but maximum
one. Thousands separators are OK, but there have to be exactly three digits
between ... etc.
I think it's better to let the user enter anything they like, then validate
the result before you use it. You can use the IsNumeric() function, but be
aware there are some strange strings that pass its test. Or simply cast the
string to the data type you want, check for error, and echo the value back
to the user.
Dim pResult as long
on error resume next
pResult = clng(TextBox)
if err > 0 then
... invalid value
exit sub
end if
on error goto 0
TextBox = cstr(pResult)
