Regular Expressions 101

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/
^(([a-zA-Z]+)([a-zA-Z0-9\.\-\_]*)([a-zA-Z]+))@(([a-zA-Z0-9]+)([a-zA-Z0-9\.\-\_]*)([a-zA-Z0-9]+)\.)([a-zA-Z0-9]{2,})$
/
^ asserts position at start of the string
1st Capturing Group
(([a-zA-Z]+)([a-zA-Z0-9\.\-\_]*)([a-zA-Z]+))
2nd Capturing Group
([a-zA-Z]+)
Match a single character present in the list below
[a-zA-Z]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
3rd Capturing Group
([a-zA-Z0-9\.\-\_]*)
Match a single character present in the list below
[a-zA-Z0-9\.\-\_]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
\- matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
\_ matches the character _ with index 9510 (5F16 or 1378) literally (case sensitive)
4th Capturing Group
([a-zA-Z]+)
Match a single character present in the list below
[a-zA-Z]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
@ matches the character @ with index 6410 (4016 or 1008) literally (case sensitive)
5th Capturing Group
(([a-zA-Z0-9]+)([a-zA-Z0-9\.\-\_]*)([a-zA-Z0-9]+)\.)
6th Capturing Group
([a-zA-Z0-9]+)
Match a single character present in the list below
[a-zA-Z0-9]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
7th Capturing Group
([a-zA-Z0-9\.\-\_]*)
Match a single character present in the list below
[a-zA-Z0-9\.\-\_]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
\- matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
\_ matches the character _ with index 9510 (5F16 or 1378) literally (case sensitive)
8th Capturing Group
([a-zA-Z0-9]+)
Match a single character present in the list below
[a-zA-Z0-9]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
9th Capturing Group
([a-zA-Z0-9]{2,})
Match a single character present in the list below
[a-zA-Z0-9]
{2,} matches the previous token between 2 and unlimited times, as many times as possible, giving back as needed (greedy)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
$ asserts position at the end of the string, or before the line terminator right at the end of the string (if any)
Your regular expression does not match the subject string.Try launching the debugger to find out why.

Regular Expression
No Match

/
/

Test String