C validating user input
C validating user input - dating love in slovenija
There are other ways to highlight the field in question besides changing the text color, the border color or the fill color could be changed instead, or in addition, just make sure that you are not making the form impossible to read.
The member ‘rc’ (or return code) is used to communicate back if the validation was successful or not.Let’s take a look at how to do that with a text field that is only supposed to have a value of either ‘AAAA’ or ‘BBBB’ (yes, I know that this does not make much sense in a real PDF form).So, if the user enters ‘01234’ we should see an error message that would instruct the user about what type of data is valid for this field.Another thing I like to do is to display the validation error message on the form in an otherwise hidden field: The problem with our last solution is that if the user saves a partially filled form, and picks it up at a later time, that error message that popped up is long gone, and the only indication that there is something wrong with the form is the modified field color.So, having a text field contain that error message might be a good idea.Input validation should be applied on both syntactical and semantic level.
Syntactic validation should enforce correct syntax of structured fields (e.g.SSN, date, currency symbol) while semantic validation should enforce correctness of their values in the specific business context (e.g.start date is before end date, price is within expected range).Data from all potentially untrusted sources should be subject to input validation, including not only Internet-facing web clients but also backend feeds over extranets, from suppliers, partners, vendors or regulators, each of which may be compromised on their own and start sending malformed data.Input Validation should not be used as the primary method of preventing XSS, SQL Injection and other attacks which are covered in respective cheat sheets but can significantly contribute to reducing their impact if implemented properly.Input validation is performed to ensure only properly formed data is entering the workflow in an information system, preventing malformed data from persisting in the database and triggering malfunction of various downstream components.