Regular Expressions 101

Non-Capturing Group(?:^|\D)

1st Alternative^

^start of line

2nd Alternative\D

\Dany character that's not a digit

Group 1(1\d{7})

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\d{7}a digit, repeated exactly 7 times

Non-Capturing Group(?:\D|$)

1st Alternative\D

\Dany character that's not a digit

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

(?:^|\D)(1\d{7})(?:\D|$)

New

a12891212a
a 12891212 a
128912120a
23456789
11233456789