Validnumber( and nan( functions not acting the way I expect

Panorama X
1

I am trying to test to see if a user entered a valid number into a text editor. (Should be a dollar amount.) The procedure that is triggered is using nan( to check. But virtually everything I enter returns false. A string of text returns false.

Nan
Nan1064×530 99.5 KB

Can someone explain what is going on? A bug or I am misunderstanding something? Is there a better to test if an entry is a valid number?

2

nan is actually a floating point value. Functions like sqr(, log(, arcsin(, and arccos(, which are undefined for certain arguments, will return a nan value when given one of those arguments. The nan( function is looking for a value of nan or inf (infinity.) It will return true() for either of those two floating point values, and false() for everything else.

3

Thanks for the explanation. Any suggestion on how to test an entry to see if it is a valid number?

4

The val( function will return 0 if it can’t interpret the string as a number. If 0 is an acceptable entry, you may need to add a specific test for that. Maybe something like

?(val(theNumber)≠0 or theNumber BeginsWith "0",true(),false())
5

You can use a regular expression for this. Assume that VALUE is a variable containing text. If you want to find out if the text is a valid integer, use this formula:

_VALUE_ regexmatch {^(\+|-)?\d+$}

If you want to find out if the text is a valid floating point number, you could use this:

_VALUE_ regexmatch {^[+-]?\d*(\}+info("decimalseparator")+{)?(\d+)?[ ]*([Ee][+-]?\d+)?$}
6

The documentation says validnumber( is the opposite function to nan(. It returns true if the value is valid, false if it is invalid.

7

Don’t spend a lot of effort here now. Data Input Validation is listed under 10.2’s coming attractions in the online help.

8

Thanks to everybody for the various suggestions and comments.