Regular Expressions 101

^start of line

\+?optionally matches the literal + (43₁₀ / 53₈ / 2B₁₆)

Non-Capturing Group(?:[1-9]\d*(?:\.\d{1,2})?|0\.(?:[1-9]\d?|\d[1-9]))

1st Alternative[1-9]\d*(?:\.\d{1,2})?

Character Class[1-9]

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

\d*a digit, repeated any number of times

Non-Capturing Group(?:\.\d{1,2})?

?repeats the group contents below at most once:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\d{1,2}a digit, repeated between 1 and 2 times

2nd Alternative0\.(?:[1-9]\d?|\d[1-9])

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:[1-9]\d?|\d[1-9])

1st Alternative[1-9]\d?

Character Class[1-9]

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

\d?optionally matches a digit

2nd Alternative\d[1-9]

\da digit

Character Class[1-9]

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

$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

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26 tokens

Regular Expression

^\+?(?:[1-9]\d*(?:\.\d{1,2})?|0\.(?:[1-9]\d?|\d[1-9]))$

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