what's the function of validator?

Answer 1

Also (since you weren't specific) there's markup validation that validates your code - like WC3 Markup Validation, that checks code you've written using HTML, XHTML, etc. The validator checks the syntax of your code to see if there are any mistakes or anything that doesn't quite follow the acceptable rules. It's possible for your code to work, say, when you test it in a browser like Internet Explorer, and yet still not validate. So, if your code works but doesn't validate, why go to the trouble of making it validate? Well, although your code might work the way you want it to in one browser (IE for example), it might not work right in another browser (say, Firefox). Making sure your code validates is one way you can minimize this problem.

Answer 2

if you are asking in .net then
..
if you need to validate some field in the textbox in a form then you can use validation for tat
eg
if you have a textbox for entering the age between 18 to 25 then
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you can set the range validator for tat textbox
so tat if the user inputs greater or smaller value then it ll show error...

Answer 3

to validate?