Regular Expressions 101

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/
(( | )*[a-zA-Z0-9!#$%&amp;'*+/=?^_`{|}~-]+(?:\.[a-zA-Z0-9!#$%&amp;'*+/=?^_`{|}~-]+)*@(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?\.)+[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?( | )*)
/
1st Capturing Group
(( | )*[a-zA-Z0-9!#$%&amp;'*+/=?^_`{|}~-]+(?:\.[a-zA-Z0-9!#$%&amp;'*+/=?^_`{|}~-]+)*@(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?\.)+[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?( | )*)
2nd Capturing Group
( | )*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
A repeated capturing group will only capture the last iteration. Put a capturing group around the repeated group to capture all iterations or use a non-capturing group instead if you're not interested in the data
1st Alternative
matches the character with index 3210 (2016 or 408) literally (case sensitive)
2nd Alternative
matches the characters literally (case sensitive)
Match a single character present in the list below
[a-zA-Z0-9!#$%&amp;'*+/=?^_`{|}~-]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
!#$%&amp;'*+/=?^_`{|}~
matches a single character in the list !#$%&amp;'*+/=?^_`{|}~ (case sensitive)
- matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
This hyphen is treated literally, which might be confusing for others. Consider escaping it or placing at the start or end of the class!
Non-capturing group
(?:\.[a-zA-Z0-9!#$%&amp;'*+/=?^_`{|}~-]+)*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
Match a single character present in the list below
[a-zA-Z0-9!#$%&amp;'*+/=?^_`{|}~-]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
!#$%&amp;'*+/=?^_`{|}~
matches a single character in the list !#$%&amp;'*+/=?^_`{|}~ (case sensitive)
- matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
This hyphen is treated literally, which might be confusing for others. Consider escaping it or placing at the start or end of the class!
@ matches the character @ with index 6410 (4016 or 1008) literally (case sensitive)
Non-capturing group
(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?\.)+
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
Match a single character present in the list below
[a-zA-Z0-9]
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)
Non-capturing group
(?:[a-zA-Z0-9-]*[a-zA-Z0-9])?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
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 4510 (2D16 or 558) literally (case sensitive)
This hyphen is treated literally, which might be confusing for others. Consider escaping it or placing at the start or end of the class!
Match a single character present in the list below
[a-zA-Z0-9]
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)
Match a single character present in the list below
[a-zA-Z0-9]
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)
Non-capturing group
(?:[a-zA-Z0-9-]*[a-zA-Z0-9])?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
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 4510 (2D16 or 558) literally (case sensitive)
This hyphen is treated literally, which might be confusing for others. Consider escaping it or placing at the start or end of the class!
Match a single character present in the list below
[a-zA-Z0-9]
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)
3rd Capturing Group
( | )*
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
A repeated capturing group will only capture the last iteration. Put a capturing group around the repeated group to capture all iterations or use a non-capturing group instead if you're not interested in the data
1st Alternative
matches the character with index 3210 (2016 or 408) literally (case sensitive)
2nd Alternative
matches the characters literally (case sensitive)
Your regular expression does not match the subject string.

Regular Expression
No Match

/
/

Test String