Regular Expressions 101

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/
^(http(s)?:\/\/)?(www.)?([a-zA-Z0-9])+([\-\.][a-zA-Z0-9])*\.[a-zA-Z](:[0-9])?(\/[^\s])?$
/
gm
^ asserts position at start of a line
1st Capturing Group
(http(s)?:\/\/)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
http matches the characters http literally (case sensitive)
2nd Capturing Group
(s)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
s matches the character s literally (case sensitive)
: matches the character : literally (case sensitive)
\/ matches the character / literally (case sensitive)
\/ matches the character / literally (case sensitive)
3rd Capturing Group
(www.)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
www matches the characters www literally (case sensitive)
. matches any character (except for line terminators)
4th Capturing Group
([a-zA-Z0-9])+
+ matches the previous token between one 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
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)
5th Capturing Group
([\-\.][a-zA-Z0-9])*
* 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
Match a single character present in the list below
[\-\.]
{1} matches the previous token exactly one time (meaningless quantifier)
\- matches the character - literally (case sensitive)
\. matches the character . literally (case sensitive)
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 . literally (case sensitive)
Match a single character present in the list below
[a-zA-Z]
{2,5} matches the previous token between 2 and 5 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)
6th Capturing Group
(:[0-9])?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
: matches the character : literally (case sensitive)
Match a single character present in the list below
[0-9]
7th Capturing Group
(\/[^\s])?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
\/ matches the character / literally (case sensitive)
Match a single character not present in the list below
[^\s]
$ asserts position at the end of a line
Global pattern flags
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
Your regular expression does not match the subject string.

Regular Expression
No Match

/
/
gm

Test String