Regular Expressions 101

Save & Share

Flavor

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

Function

  • Match
  • Substitution
  • List
  • Unit Tests
/
^\(?[1-9]{2}\)?( ?)?([1-9]{1}[0-9]{3}|[0-9]{3}) ?[0-9]{4}$
/
gm
^ asserts position at start of a line
\(
matches the character ( with index 4010 (2816 or 508) literally (case sensitive)
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
Match a single character present in the list below
[1-9]
{2} matches the previous token exactly 2 times
1-9 matches a single character in the range between 1 (index 49) and 9 (index 57) (case sensitive)
\)
matches the character ) with index 4110 (2916 or 518) literally (case sensitive)
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
1st Capturing Group
( ?)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
matches the character with index 3210 (2016 or 408) literally (case sensitive)
2nd Capturing Group
([1-9]{1}[0-9]{3}|[0-9]{3})
1st Alternative
[1-9]{1}[0-9]{3}
Match a single character present in the list below
[1-9]
{1} matches the previous token exactly one time (meaningless quantifier)
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]
{3} matches the previous token exactly 3 times
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
2nd Alternative
[0-9]{3}
Match a single character present in the list below
[0-9]
{3} matches the previous token exactly 3 times
0-9 matches a single character in the range between 0 (index 48) and 9 (index 57) (case sensitive)
matches the character with index 3210 (2016 or 408) literally (case sensitive)
Match a single character present in the list below
[0-9]
{4} matches the previous token exactly 4 times
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 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.Try launching the debugger to find out why.

Regular Expression
No Match

/
/
gm

Test String