Regular Expressions 101

Pro

^start of line

Character Class[a-z_]

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Character Class[a-z0-9_]{0,99}

{0,99}matches between 0 and 99 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

$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

^[a-z_][a-z0-9_]{0,99}$

New

r2_d2
1nonumberstart
r2d2_
_r2r2
too_long_r2d2_cool_1_r2d2_cool_1_r2d2_cool_1_r2d2_cool_1_r2d2_cool_1_r2d2_cool_1_r2d2_cool_1_r2d2_cool_1

r2_d2
1nonumberstart
r2d2_
_r2r2
too_long_r2d2_cool_1_r2d2_cool_1_r2d2_cool_1_r2d2_cool_1_r2d2_cool_1_r2d2_cool_1_r2d2_cool_1_r2d2_cool_1