Regular Expressions 101

Explanation

Pro

^start of string

Non-Capturing Group(?:(?:(?:https?|ftp):)?\/\/)

Non-Capturing Group(?:(?:https?|ftp):)?

?repeats the group contents below at most once:

Non-Capturing Group(?:https?|ftp)

1st Alternativehttps?

httpthe literal text http (case insensitive)

s?optionally matches the literal s (115₁₀ / 163₈ / 73₁₆) (case insensitive)

2nd Alternativeftp

ftpthe literal text ftp (case insensitive)

:the literal : (58₁₀ / 72₈ / 3A₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

Non-Capturing Group(?:\S+(?::\S*)?@)?

?repeats the group contents below at most once:

\S+any character that is not Unicode whitespace, repeated at least once

Non-Capturing Group(?::\S*)?

?repeats the group contents below at most once:

:the literal : (58₁₀ / 72₈ / 3A₁₆)

\S*any character that is not Unicode whitespace, repeated any number of times

@the literal @ (64₁₀ / 100₈ / 40₁₆)

Non-Capturing Group(?:(?!(?:10|127)(?:\.\d{1,3}){3})(?!(?:169\.254|192\.168)(?:\.\d{1,3}){2})(?!172\.(?:1[6-9]|2\d|3[0-1])(?:\.\d{1,3}){2})(?:[1-9]\d?|1\d\d|2[01]\d|22[0-3])(?:\.(?:1?\d{1,2}|2[0-4]\d|25[0-5])){2}(?:\.(?:[1-9]\d?|1\d\d|2[0-4]\d|25[0-4]))|(?:(?:[a-z0-9\x{00a1}-\x{ffff}][a-z0-9\x{00a1}-\x{ffff}_-]{0,62})?[a-z0-9\x{00a1}-\x{ffff}]\.)+(?:[a-z\x{00a1}-\x{ffff}]{2,}\.?))

1st Alternative(?!(?:10|127)(?:\.\d{1,3}){3})(?!(?:169\.254|192\.168)(?:\.\d{1,3}){2})(?!172\.(?:1[6-9]|2\d|3[0-1])(?:\.\d{1,3}){2})(?:[1-9]\d?|1\d\d|2[01]\d|22[0-3])(?:\.(?:1?\d{1,2}|2[0-4]\d|25[0-5])){2}(?:\.(?:[1-9]\d?|1\d\d|2[0-4]\d|25[0-4]))

Negative Lookahead(?!(?:10|127)(?:\.\d{1,3}){3})

Non-Capturing Group(?:10|127)

1st Alternative10

10the literal text 10

2nd Alternative127

127the literal text 127

Non-Capturing Group(?:\.\d{1,3}){3}

{3}repeats the group contents below exactly 3 times:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

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

Negative Lookahead(?!(?:169\.254|192\.168)(?:\.\d{1,3}){2})

Non-Capturing Group(?:169\.254|192\.168)

1st Alternative169\.254

169the literal text 169

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

254the literal text 254

2nd Alternative192\.168

192the literal text 192

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

168the literal text 168

Non-Capturing Group(?:\.\d{1,3}){2}

{2}repeats the group contents below exactly 2 times:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

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

Negative Lookahead(?!172\.(?:1[6-9]|2\d|3[0-1])(?:\.\d{1,3}){2})

172the literal text 172

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:1[6-9]|2\d|3[0-1])

1st Alternative1[6-9]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[6-9]

6-9one character from 6 (54₁₀) to 9 (57₁₀)

2nd Alternative2\d

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

\da Unicode decimal digit

3rd Alternative3[0-1]

3the literal 3 (51₁₀ / 63₈ / 33₁₆)

Character Class[0-1]

Non-Capturing Group(?:\.\d{1,3}){2}

Non-Capturing Group(?:[1-9]\d?|1\d\d|2[01]\d|22[0-3])

Non-Capturing Group(?:\.(?:1?\d{1,2}|2[0-4]\d|25[0-5])){2}

Non-Capturing Group(?:\.(?:[1-9]\d?|1\d\d|2[0-4]\d|25[0-4]))

2nd Alternative(?:(?:[a-z0-9\x{00a1}-\x{ffff}][a-z0-9\x{00a1}-\x{ffff}_-]{0,62})?[a-z0-9\x{00a1}-\x{ffff}]\.)+(?:[a-z\x{00a1}-\x{ffff}]{2,}\.?)

Non-Capturing Group(?::\d{2,5})?

Non-Capturing Group(?:[/?#]\S*)?

$end of string, or before its final line terminator

Global pattern flags

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

u modifier: unicode. Treats the pattern and subject as UTF-16

Unit Test Summary

Ready to run

Quick Reference

25 tokens

Regular Expression

^(?:(?:(?:https?|ftp):)?\/\/)(?:\S+(?::\S*)?@)?(?:(?!(?:10|127)(?:\.\d{1,3}){3})(?!(?:169\.254|192\.168)(?:\.\d{1,3}){2})(?!172\.(?:1[6-9]|2\d|3[0-1])(?:\.\d{1,3}){2})(?:[1-9]\d?|1\d\d|2[01]\d|22[0-3])(?:\.(?:1?\d{1,2}|2[0-4]\d|25[0-5])){2}(?:\.(?:[1-9]\d?|1\d\d|2[0-4]\d|25[0-4]))|(?:(?:[a-z0-9\x{00a1}-\x{ffff}][a-z0-9\x{00a1}-\x{ffff}_-]{0,62})?[a-z0-9\x{00a1}-\x{ffff}]\.)+(?:[a-z\x{00a1}-\x{ffff}]{2,}\.?))(?::\d{2,5})?(?:[/?#]\S*)?$

Unit Tests