Regular Expressions 101

Positive Lookbehind(?<=[ \t])

Character Class[ \t]

the literal (32₁₀ / 40₈ / 20₁₆)

\ta tab character (ASCII 9)

Group 1((?:\d{5}(?=[^\d-]|$))|(?:\d{5}-\d{4}(?=[^\d-]|$)))

1st Alternative(?:\d{5}(?=[^\d-]|$))

Non-Capturing Group(?:\d{5}(?=[^\d-]|$))

\d{5}a Unicode decimal digit, repeated exactly 5 times

Positive Lookahead(?=[^\d-]|$)

1st Alternative[^\d-]

Negated Character Class[^\d-]

\da Unicode decimal digit

-the literal - (45₁₀ / 55₈ / 2D₁₆)

2nd Alternative$

$end of line

2nd Alternative(?:\d{5}-\d{4}(?=[^\d-]|$))

Non-Capturing Group(?:\d{5}-\d{4}(?=[^\d-]|$))

\d{5}a Unicode decimal digit, repeated exactly 5 times

-the literal - (45₁₀ / 55₈ / 2D₁₆)

\d{4}a Unicode decimal digit, repeated exactly 4 times

Positive Lookahead(?=[^\d-]|$)

1st Alternative[^\d-]

Negated Character Class[^\d-]

\da Unicode decimal digit

-the literal - (45₁₀ / 55₈ / 2D₁₆)

2nd Alternative$

$end of line

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

Detailed match information will be displayed here automatically.

Search reference

Regular Expression

(?<=[ \t])((?:\d{5}(?=[^\d-]|$))|(?:\d{5}-\d{4}(?=[^\d-]|$)))

New

Should match:
 92120
 11345-1234

Should not match:

92120
 1234567 
 11345-1234567