Data Validation for email address?

[Lea Valentine]

I'm having a hard time with the requirements asked of me since I'm really new to programming. What I'm making is a windows application. I've been able to have data validations for only one @ sign and the string not starting with a period or symbol, but I'm having problems with two things:

1. Having only 1 period AFTER the single @ but allowing more than one before it.
2. Preventing the user from entering multiple periods (the hint was that I could use something similar to trim functions -- I'm using a custom trim function for spaces)

What I've been taught was to use either Keypress or TextChanged event and put the codes there. I would like to know where to start.

[GaryTexmo]

This sounds a bit like a homework assignment and this forum has pretty strict rules about helping people with homework assignments. I can't really give you answers here but maybe I can give you a few nudges in the right direction.

1) If there's no requirement on how you need to approach this, it might be a good idea to have a look into using Regular Expressions to validate your e-mail string. They were made for this kind of thing so you might find that helpful.

2) If you absolutely must do it with string functions, you are doing it on the TextChanged event (or KeyPress) so you know what characters are coming. Perhaps keeping counts and setting flags might be appropriate? Also have a look at the string.Contains and string.IndexOf methods.

3) You mentioned preventing the user from entering multiple periods... is that correct? An e-mail of "[e-mail]" is valid, I believe. So is "alberta.government.emails.may.look.like.this@gov. ab.ca". You may wish to clarify on that requirement.

Good luck!