Test if the user typed email format ASP.NET (VB)

I have a TextBox, and I want to fo开发者_运维知识库rce the user to type an email format in this field like (example@mail.com) ?

I don't want to use FilteredTextBoxExtender or the RegularExpressionValidator.

I want to do it manualy.

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Use the MailAddress class of System.Net.Mail. If what you pass into it is not a valid email address it will fail.

Example:

How do I validate email address formatting with the .NET Framework?

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You are really going to reinvent the wheel. But if it is your wish, you have to use string manipulation functions built in to the String object.

First do a check whether there is a in @ symbol in the text.

Use String.Contains to check that.

Or you can use String.IndexOf to check whether the @ symbol is present, and if present which index is it present. (considering the string as an array of characters)

And then check whether there are any (and how many) characters present before the @ symbol. If the symbol @ symbol was in the 4th index, then you know there are 3 characters before etc.

There's plethora of functions for the String object. You may have to use Length function and String.SubString to retrieve parts of the string.

Get the indexes of the @ symbol and the . symbol and check whether there are at least 3 characters in between.

I really cant seem to think of all the possibilities but first list down all the possibilities and check them one by one.

You can also use the Contains method to check whether illegal characters are present :)

EDIT: String.LastIndexOf will return the last index where a specified character was found ;)

And you count and check whether the @ symbol was found more than once etc

String.IndexOfAny(Char[])

String.IndexOfAny Method (Char[], Int32)

String.IndexOfAny Method (Char[], Int32, Int32)

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This is the best way I found on internet.

Regex.IsMatch(YourStringEmail, "^(?("")("".+?""@)|(([0-9a-zA-Z]((\.(?!\.))|[-!#\$%&'\*\+/=\?\^`\{\}\|~\w])*)(?<=[0-9a-zA-Z])@))" + _
                  "(?(\[)(\[(\d{1,3}\.){3}\d{1,3}\])|(([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,6}))$")

Thank you.