Regular Expressions 101

^start of line

Non-Capturing Group(?:(?:[1-9]|1[0-2])(?:,|$)){0,12}

{0,12}repeats the group contents below between 0 and 12 times:

Non-Capturing Group(?:[1-9]|1[0-2])

1st Alternative[1-9]

Character Class[1-9]

1-9one character from 1 (49₁₀) to 9 (57₁₀)

2nd Alternative1[0-2]

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[0-2]

0-2one character from 0 (48₁₀) to 2 (50₁₀)

Non-Capturing Group(?:,|$)

1st Alternative,

,the literal , (44₁₀ / 54₈ / 2C₁₆)

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

^(?:(?:[1-9]|1[0-2])(?:,|$)){0,12}$

1,2,3
1,02,3
1,2,3,
1,2,,3
,1,2,3
1,2,3,4,5,6,7,8,9,10,11,12
1,2,3,4,5,6,7,8,9,10,11,12,1
1,2,3,4,5,6,7,8,9,12
1,2,3,4,5,6,7,8,9,13
12,11,10