Invalid data in number fields

The problem is that if you insert text into a number input box (integer or decimal), it replaces your text with the number 0 and stores this into your content.
This is done quietly and the user is not informed that their data was invalid, and that something different was stored into the database.
The text is invalid and should be marked as so, requiring that the user fix the error.

Traced the problem to a regular expression replace that replaced essentially any non-integer with an empty string quietly. Removed this and created a 'is_numeric' check in the number validate function.