Testing for numerics

[Dar Scott]

On Sep 30, 2006, at 12:56 PM, Francis Nugent Dixon wrote:

> I want to check the contents of a field for numeric,
> so, for a field of four characters, I coded :
>
>  matchText(field MyTextField,"[0-9][0-9][0-9][0-9]")
>  if it is true then ......
>
> Is this the right way to check for numerics, and if
> so, what have I done wrong ?

Revolution defines matchText as a function.  The above script will  
look for a command named matchText.  (An implied 'get' does sound  
like an interesting idea.)

So, first of all, change the above to this:

    get matchText(field MyTextField,"[0-9][0-9][0-9][0-9]")
    if it is true then ......

This is also OK, if you are content with the readability:

    get matchText(field MyTextField,"[0-9][0-9][0-9][0-9]")
    if it then ......

Or this:

    if matchText(field MyTextField,"[0-9][0-9][0-9][0-9]") then ......

That will match text that contains 4 digits in a row and so will  
match "around 1966 or so" or "4/5/1966".  Perhaps this does what you  
want:

    if matchText(field MyTextField,"\A[0-9]{4}\z") then ......

The \A and \z match at the start and end respectively.  The {4} means  
exactly 4 times.

You might want to consider "is a number".  Use it like this:

    if field MyTextField is a number then ......

That will match some numerals that you might not expect, such as  
"1.3", "1.0E01", "+inf" (on OS X) and "0xF0E".