Regular Expressions 101

^start of line

Positive Lookahead(?=(?:[^a-zA-Z\n]*[a-zA-Z]){4}[^a-zA-Z\n]*$)

Non-Capturing Group(?:[^a-zA-Z\n]*[a-zA-Z]){4}

{4}repeats the group contents below exactly 4 times:

Negated Character Class[^a-zA-Z\n]*

*matches any number of characters outside the set below:

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

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

\na line-feed (newline) character (ASCII 10)

Character Class[a-zA-Z]

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

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

Negated Character Class[^a-zA-Z\n]*

*matches any number of characters outside the set below:

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

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

\na line-feed (newline) character (ASCII 10)

$end of line

Positive Lookahead(?=(?:[^\d\n]*\d){3}[^\d\n]*$)

Non-Capturing Group(?:[^\d\n]*\d){3}

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

Negated Character Class[^\d\n]*

*matches any number of characters outside the set below:

\da Unicode decimal digit

\na line-feed (newline) character (ASCII 10)

\da Unicode decimal digit

Negated Character Class[^\d\n]*

*matches any number of characters outside the set below:

\da Unicode decimal digit

\na line-feed (newline) character (ASCII 10)

$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.

Search reference

Regular Expression

^(?=(?:[^a-zA-Z\n]*[a-zA-Z]){4}[^a-zA-Z\n]*$)(?=(?:[^\d\n]*\d){3}[^\d\n]*$)

New

t1E2S3T
t1E2S33

$1