# Regular Expressions 101

• Save Regex
ctrl+s

## Flavor

• PCRE2 (PHP >=7.3)
• PCRE (PHP <7.3)
• ECMAScript (JavaScript)
• Python
• Golang
• Java 8

## Function

• Match
• Substitution
• List
• Unit Tests (17)

## Tools

/
^\s*(([+]?(0|[1-9][0-9]*)([Ee][+]?[0-9]+)?\s+){2}[+]?[0-4](\s+(0x[0-9a-fA-F]{1,16}|[+]?(0|[1-9][0-9]*)([Ee][+]?[0-9]+)?))*\s*,?\s*)*\$
/
gm
^ asserts position at start of a line
\s
matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
1st Capturing Group
(([+]?(0|[1-9][0-9]*)([Ee][+]?[0-9]+)?\s+){2}[+]?[0-4](\s+(0x[0-9a-fA-F]{1,16}|[+]?(0|[1-9][0-9]*)([Ee][+]?[0-9]+)?))*\s*,?\s*)*
* 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
2nd Capturing Group
([+]?(0|[1-9][0-9]*)([Ee][+]?[0-9]+)?\s+){2}
{2} matches the previous token exactly 2 times
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
[+]
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
+ matches the character + with index 4310 (2B16 or 538) literally (case sensitive)
3rd Capturing Group
(0|[1-9][0-9]*)
1st Alternative
0
0 matches the character 0 with index 4810 (3016 or 608) literally (case sensitive)
2nd Alternative
[1-9][0-9]*
Match a single character present in the list below
[1-9]
1-9 matches a single character in the range between 1 (index 49) and 9 (index 57) (case sensitive)
Match a single character present in the list below
[0-9]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
4th Capturing Group
([Ee][+]?[0-9]+)?
? 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
[Ee]
Ee
matches a single character in the list Ee (case sensitive)
Match a single character present in the list below
[+]
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
+ matches the character + with index 4310 (2B16 or 538) literally (case sensitive)
Match a single character present in the list below
[0-9]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
+ 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
[+]
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
+ matches the character + with index 4310 (2B16 or 538) literally (case sensitive)
Match a single character present in the list below
[0-4]
0-4 matches a single character in the range between 0 (index 48) and 4 (index 52) (case sensitive)
5th Capturing Group
(\s+(0x[0-9a-fA-F]{1,16}|[+]?(0|[1-9][0-9]*)([Ee][+]?[0-9]+)?))*
* 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
\s
matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
6th Capturing Group
(0x[0-9a-fA-F]{1,16}|[+]?(0|[1-9][0-9]*)([Ee][+]?[0-9]+)?)
1st Alternative
0x[0-9a-fA-F]{1,16}
0x
matches the characters 0x literally (case sensitive)
Match a single character present in the list below
[0-9a-fA-F]
{1,16} matches the previous token between 1 and 16 times, as many times as possible, giving back as needed (greedy)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
a-f matches a single character in the range between a (index 97) and f (index 102) (case sensitive)
A-F matches a single character in the range between A (index 65) and F (index 70) (case sensitive)
2nd Alternative
[+]?(0|[1-9][0-9]*)([Ee][+]?[0-9]+)?
Match a single character present in the list below
[+]
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
+ matches the character + with index 4310 (2B16 or 538) literally (case sensitive)
7th Capturing Group
(0|[1-9][0-9]*)
1st Alternative
0
0 matches the character 0 with index 4810 (3016 or 608) literally (case sensitive)
2nd Alternative
[1-9][0-9]*
Match a single character present in the list below
[1-9]
1-9 matches a single character in the range between 1 (index 49) and 9 (index 57) (case sensitive)
Match a single character present in the list below
[0-9]
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
8th Capturing Group
([Ee][+]?[0-9]+)?
? 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
[Ee]
Ee
matches a single character in the list Ee (case sensitive)
Match a single character present in the list below
[+]
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
+ matches the character + with index 4310 (2B16 or 538) literally (case sensitive)
Match a single character present in the list below
[0-9]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
,
matches the character , with index 4410 (2C16 or 548) literally (case sensitive)
\s
matches any whitespace character (equivalent to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
* matches the previous token between zero and unlimited times, as many times as possible, giving back as needed (greedy)
\$ 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.

/
/
gm