Regular Expressions 101

Negative Lookbehind(?<!\d)

\da Unicode decimal digit

Non-Capturing Group(?:(?:(?:(4[0-9]{12}(?:[0-9]{3})?))|(3[47][0-9]{13})|(?:5[1-5][0-9]{14}))(?!\d))

Non-Capturing Group(?:(?:(4[0-9]{12}(?:[0-9]{3})?))|(3[47][0-9]{13})|(?:5[1-5][0-9]{14}))

1st Alternative(?:(4[0-9]{12}(?:[0-9]{3})?))

Non-Capturing Group(?:(4[0-9]{12}(?:[0-9]{3})?))

Group 1(4[0-9]{12}(?:[0-9]{3})?)

4the literal 4 (52₁₀ / 64₈ / 34₁₆)

Character Class[0-9]{12}

{12}matches exactly 12 characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Non-Capturing Group(?:[0-9]{3})?

?repeats the group contents below at most once:

Character Class[0-9]{3}

{3}matches exactly 3 characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

2nd Alternative(3[47][0-9]{13})

Group 2(3[47][0-9]{13})

3the literal 3 (51₁₀ / 63₈ / 33₁₆)

Character Class[47]

4the literal 4 (52₁₀ / 64₈ / 34₁₆)

7the literal 7 (55₁₀ / 67₈ / 37₁₆)

Character Class[0-9]{13}

{13}matches exactly 13 characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

3rd Alternative(?:5[1-5][0-9]{14})

Non-Capturing Group(?:5[1-5][0-9]{14})

5the literal 5 (53₁₀ / 65₈ / 35₁₆)

Character Class[1-5]

1-5one character from 1 (49₁₀) to 5 (53₁₀)

Character Class[0-9]{14}

{14}matches exactly 14 characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Negative Lookahead(?!\d)

\da Unicode decimal digit

Global pattern flags

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

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

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Search reference

Regular Expression

(?<!\d)(?:(?:(?:(4[0-9]{12}(?:[0-9]{3})?))|(3[47][0-9]{13})|(?:5[1-5][0-9]{14}))(?!\d))

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