Regular Expressions 101

Explanation

Pro

Non-Capturing Group(?:[^-]|^)

1st Alternative[^-]

Negated Character Class[^-]

-the literal - (45₁₀ / 55₈ / 2D₁₆)

2nd Alternative^

^start of line

Group 1(1(?:-1)+)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Non-Capturing Group(?:-1)+

+repeats the group contents below at least once:

-1the literal text -1

Negative Lookahead(?!-)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

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.

26 tokens

(?:[^-]|^)(1(?:-1)+)(?!-)

New

1-1-1 and 1-1-1-1-1 but not -1-1-1-1 or 1-1-1-1-

1-1-1
1-1-1-1-1
-1-1-1-1
1-1-1-1-

1-1-1 and 1-1-1-1-1 but not -1-1-1-1 or 1-1-1-1-

1-1-1
1-1-1-1-1
-1-1-1-1
1-1-1-1-