Tutorial for Regex Statement

gistfile1.txt

# Tutorial for Regex statement

Introductory paragraph (replace this with your text)

## Summary
I will explain each piece of this regex which can identify an email address /^([a-z0-9_\.-]+)@([\da-z\.-]+)\.([a-z\.]{2,6})$/

We'll start with the first characters here, ^ matches the position at the start of the string.
([a-z0-9_\.-]+) is the first capture group.
This group matches the group between one and unlimited times giving back as necessary, considered greedy.  The group matches as follows:
    * a-z matches a single char between a and z case sensitive.
    * 0-9 matches a single char between 0 and 9 case sensitive.
    * _ matches _ literally.
    * \. matches . literally.
    * - matches - literally.

@ is next, it is matched literally.

The second capture group ([\da-z\.-]+) again has the plus, which makes it return as many times as possible, again greedy.
[\da-z\.-] matches a single char in the list below:
    * \d matches a digit, equiv to [0-9]
    * a-z matches a single char between a and z case sensitive.
    * \. matches . literally.
    * - matches - literally.

\. matches . literally

The third, and final, capture group ([a-z\.]{2,6}) matches a single character in the list below between 2 and 6 times {2,6}:
    * a-z matches a single char between a and z case sensitive.
    * \. matches the character . literally.

$ asserts the position at the end of the string