Regular Expressions 101

Pro

^start of string

Non-Capturing Group(?:\D+)?

?repeats the group contents below at most once:

\D+any character that's not a digit, repeated at least once

Non-Capturing Group(?:(?:[4-7](?:(?:\.|\,)[1-9])?)|(?:[5-8](?:(?:\.|\,)0)?))

1st Alternative(?:[4-7](?:(?:\.|\,)[1-9])?)

Non-Capturing Group(?:[4-7](?:(?:\.|\,)[1-9])?)

Character Class[4-7]

4-7one character from 4 (52₁₀) to 7 (55₁₀)

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

?repeats the group contents below at most once:

Non-Capturing Group(?:\.|\,)

1st Alternative\.

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

2nd Alternative\,

\,the literal , (44₁₀ / 54₈ / 2C₁₆)

Character Class[1-9]

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

2nd Alternative(?:[5-8](?:(?:\.|\,)0)?)

Non-Capturing Group(?:[5-8](?:(?:\.|\,)0)?)

Character Class[5-8]

5-8one character from 5 (53₁₀) to 8 (56₁₀)

Non-Capturing Group(?:(?:\.|\,)0)?

?repeats the group contents below at most once:

Non-Capturing Group(?:\.|\,)

1st Alternative\.

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

2nd Alternative\,

\,the literal , (44₁₀ / 54₈ / 2C₁₆)

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

Non-Capturing Group(?:(?:\s?gb)|\s?giga|\sgigabyte)?

?repeats the group contents below at most once:

1st Alternative(?:\s?gb)

Non-Capturing Group(?:\s?gb)

\s?optionally matches any whitespace character

gbthe literal text gb (case insensitive)

2nd Alternative\s?giga

\s?optionally matches any whitespace character

gigathe literal text giga (case insensitive)

3rd Alternative\sgigabyte

\sany whitespace character

gigabytethe literal text gigabyte (case insensitive)

Non-Capturing Group(?:.*)

.*any character, repeated any number of times

Global pattern flags

s modifier: single line. Allows a dot to match line terminators

i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters

Ready to run

25 tokens

Regular Expression

^(?:\D+)?(?:(?:[4-7](?:(?:\.|\,)[1-9])?)|(?:[5-8](?:(?:\.|\,)0)?))(?:(?:\s?gb)|\s?giga|\sgigabyte)?(?:.*)

Regular Expression

Unit Tests