Regular Expressions 101

Explanation
Pro

^start of line

Negated Character Class[^_]*

*matches any number of characters outside the set below:

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Group 1(_[^_]*){3}

{3}repeats the group contents below exactly 3 times:

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Negated Character Class[^_]*

*matches any number of characters outside the set below:

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

Negated Character Class[^_]*

*matches any number of characters outside the set below:

_the literal _ (95₁₀ / 137₈ / 5F₁₆)

$end of line

Global pattern flags

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

g modifier: global. Finds all matches instead of stopping after the first

Detailed match information will be displayed here automatically.

25 tokens

^[^_]*(_[^_]*){3}[^_]*$

New

date_name1_name2_name3_extra
date_name1_name2_name3
date_name1_name2_name3_extra
date_name1_name2_name3_extra
date_name1_name2_name3