Combining regular expressions c#

Question

I'm trying to make simple email validation by myself. And I need to combine two patterns:

1) @"^[A-Za-z0-9][A-Za-z0-9._-]+[A-Za-z0-9]@[A-Za-z0-9][A-Za-z0-9.-]+\.[A-Za-z0-9.-]+[A-Za-z0-9]$" // allows only xxxx@xxx.xx and dot is not the first or last charachter of local and domain part

2) @"^([^\.]|([^\.])\.[^\.])*$" // there must not be two or more dots in a row.

In other words, I want to add to the first regex a condition that asd.asd@asd.com is true, but asd..asd@asd.com is false.

Why don't you just execute the regex for each of them separately, and not worry about combining them into one — Sam I am says Reinstate Monica, Sep 16 '16 at 16:00
Why reinventing the wheel? http://stackoverflow.com/questions/16167983/best-regular-expression-for-email-validation-in-c-sharp — Fabjan, Sep 16 '16 at 16:02
But then I'll never know how it works;) I could use thousands of loops instead of a regex then — cepbuch, Sep 16 '16 at 16:04
Consider this: https://hackernoon.com/the-100-correct-way-to-validate-email-addresses-7c4818f24643#.bswbyuazj — yihangho, Sep 16 '16 at 16:17

score 1 · Accepted Answer · answered Sep 16 '16 at 16:01

1

^(?!.*[.][.])[A-Za-z0-9][A-Za-z0-9._-]+[A-Za-z0-9]@[A-Za-z0-9][A-Za-z0-9.-]+.[A-Za-z0-9.-]+[A-Za-z0-9]$

Just add a lookahead for the same.

See demo.

https://regex101.com/r/dR4pQ2/1

answered Sep 16 '16 at 16:01

vks

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Combining regular expressions c#

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