Regular Expressions 101

^start of string

Character Class[0-9]{2,}

{2,}matches at least 2 characters from the set below:

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

\\the literal \ (92₁₀ / 134₈ / 5C₁₆)

Character Class[0-9]{2}

{2}matches exactly 2 characters from the set below:

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

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

Group 1((?=5[15]00)[0-9]{4}\-[0-9]{3}\-|[0-9]{4}\-|(?!5[15]00)[0-9]{4}\-[0-9]{3}\-[0-9]{2})

1st Alternative(?=5[15]00)[0-9]{4}\-[0-9]{3}\-

Positive Lookahead(?=5[15]00)

5the literal 5 (53₁₀ / 65₈ / 35₁₆)

Character Class[15]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

5the literal 5 (53₁₀ / 65₈ / 35₁₆)

00the literal text 00

Character Class[0-9]{4}

{4}matches exactly 4 characters from the set below:

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

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[0-9]{3}

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

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

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

2nd Alternative[0-9]{4}\-

Character Class[0-9]{4}

{4}matches exactly 4 characters from the set below:

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

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

3rd Alternative(?!5[15]00)[0-9]{4}\-[0-9]{3}\-[0-9]{2}

Negative Lookahead(?!5[15]00)

5the literal 5 (53₁₀ / 65₈ / 35₁₆)

Character Class[15]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

5the literal 5 (53₁₀ / 65₈ / 35₁₆)

00the literal text 00

Character Class[0-9]{4}

{4}matches exactly 4 characters from the set below:

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

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[0-9]{3}

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

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

\-the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[0-9]{2}

{2}matches exactly 2 characters from the set below:

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

$end of string, or before its final line terminator

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Search reference

Regular Expression

^[0-9]{2,}\\[0-9]{2}\-((?=5[15]00)[0-9]{4}\-[0-9]{3}\-|[0-9]{4}\-|(?!5[15]00)[0-9]{4}\-[0-9]{3}\-[0-9]{2})$

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