Regular Expressions 101

Explanation

Pro

^start of line

Positive Lookahead(?=(?:\+|0{2})?(?:(?:[\(\-\)\t\f ]*\d){7,10})?(?:[\t\f ]?\d{2,3})(?:[\-\s]?[ext]{1,3}[\-\t\f ]?\d{1,4})?$)

Non-Capturing Group(?:\+|0{2})?

?repeats the group contents below at most once:

1st Alternative\+

\+the literal + (43₁₀ / 53₈ / 2B₁₆)

2nd Alternative0{2}

0{2}the literal 0 (48₁₀ / 60₈ / 30₁₆) , repeated exactly 2 times

Non-Capturing Group(?:(?:[\(\-\)\t\f ]*\d){7,10})?

?repeats the group contents below at most once:

Non-Capturing Group(?:[\(\-\)\t\f ]*\d){7,10}

{7,10}repeats the group contents below between 7 and 10 times:

Character Class[\(\-\)\t\f ]*

*matches any number of characters from the set below:

\(the literal ( (40₁₀ / 50₈ / 28₁₆)

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

\)the literal ) (41₁₀ / 51₈ / 29₁₆)

\ta tab character (ASCII 9)

\fa form-feed character (ASCII 12)

the literal (32₁₀ / 40₈ / 20₁₆)

\da digit

Non-Capturing Group(?:[\t\f ]?\d{2,3})

Character Class[\t\f ]?

?matches at most one character from the set below:

\ta tab character (ASCII 9)

\fa form-feed character (ASCII 12)

the literal (32₁₀ / 40₈ / 20₁₆)

\d{2,3}a digit, repeated between 2 and 3 times

Non-Capturing Group(?:[\-\s]?[ext]{1,3}[\-\t\f ]?\d{1,4})?

?repeats the group contents below at most once:

Character Class[\-\s]?

?matches at most one character from the set below:

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

\sany whitespace character

Character Class[ext]{1,3}

{1,3}matches between 1 and 3 characters from the set below:

ethe literal e (101₁₀ / 145₈ / 65₁₆) (case insensitive)

xthe literal x (120₁₀ / 170₈ / 78₁₆) (case insensitive)

tthe literal t (116₁₀ / 164₈ / 74₁₆) (case insensitive)

Character Class[\-\t\f ]?

?matches at most one character from the set below:

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

\ta tab character (ASCII 9)

\fa form-feed character (ASCII 12)

the literal (32₁₀ / 40₈ / 20₁₆)

\d{1,4}a digit, repeated between 1 and 4 times

$end of line

Group 1((?:\+|0{2})\d{0,3})?

?repeats the group contents below at most once:

Non-Capturing Group(?:\+|0{2})

1st Alternative\+

\+the literal + (43₁₀ / 53₈ / 2B₁₆)

2nd Alternative0{2}

0{2}the literal 0 (48₁₀ / 60₈ / 30₁₆) , repeated exactly 2 times

\d{0,3}a digit, repeated between 0 and 3 times

Non-Capturing Group(?:[\-\t\f ]?)

Character Class[\-\t\f ]?

?matches at most one character from the set below:

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

\ta tab character (ASCII 9)

\fa form-feed character (ASCII 12)

the literal (32₁₀ / 40₈ / 20₁₆)

Group 2(\(0?\d{1,3}\)|\d{0,3})

1st Alternative\(0?\d{1,3}\)

\(the literal ( (40₁₀ / 50₈ / 28₁₆)

0?optionally matches the literal 0 (48₁₀ / 60₈ / 30₁₆)

\d{1,3}a digit, repeated between 1 and 3 times

\)the literal ) (41₁₀ / 51₈ / 29₁₆)

2nd Alternative\d{0,3}

\d{0,3}a digit, repeated between 0 and 3 times

Non-Capturing Group(?:[\-\t\f ]{0,2}\d){3,}

{3,}repeats the group contents below at least 3 times:

Character Class[\-\t\f ]{0,2}

{0,2}matches between 0 and 2 characters from the set below:

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

\ta tab character (ASCII 9)

\fa form-feed character (ASCII 12)

the literal (32₁₀ / 40₈ / 20₁₆)

\da digit

Non-Capturing Group(?:[\-\s]?(?:x|ext)[\-\t\f ]?(\d{1,4}))?

?repeats the group contents below at most once:

Character Class[\-\s]?

Non-Capturing Group(?:x|ext)

Character Class[\-\t\f ]?

Group 3(\d{1,4})

$end of line

Global pattern flags

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

g modifier: global. Finds all matches instead of stopping after the first

Unit Test Summary

Ready to run

Quick Reference

25 tokens

Regular Expression

^(?=(?:\+|0{2})?(?:(?:[\(\-\)\t\f ]*\d){7,10})?(?:[\t\f ]?\d{2,3})(?:[\-\s]?[ext]{1,3}[\-\t\f ]?\d{1,4})?$)((?:\+|0{2})\d{0,3})?(?:[\-\t\f ]?)(\(0?\d{1,3}\)|\d{0,3})(?:[\-\t\f ]{0,2}\d){3,}(?:[\-\s]?(?:x|ext)[\-\t\f ]?(\d{1,4}))?$

Unit Tests