Regular Expressions 101

Pro

^start of line

Negative Lookahead(?!0*1\.0+$)

0*the literal 0 (48₁₀ / 60₈ / 30₁₆) , repeated any number of times

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

0+the literal 0 (48₁₀ / 60₈ / 30₁₆) , repeated at least once

$end of line

Positive Lookahead(?=0*[1-9])

0*the literal 0 (48₁₀ / 60₈ / 30₁₆) , repeated any number of times

Character Class[1-9]

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

\d{1,3}a digit, repeated between 1 and 3 times

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

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

$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.

25 tokens

^(?!0*1\.0+$)(?=0*[1-9])\d{1,3}\.\d{4}$

New

0.0000
0.9999
1.0000
01.0000
001.0000
000.9999

1.0009
01.0009
011.0000
0000000222.0000