Regular Expressions 101

<tag>the literal text <tag> (case sensitive)

Positive Lookahead(?=(?:(?!<\/?tag>).)*?<b>)

Non-Capturing Group(?:(?!<\/?tag>).)*?

*?repeats the group contents below any number of times:

Negative Lookahead(?!<\/?tag>)

<the literal < (60₁₀ / 74₈ / 3C₁₆)

\/?optionally matches the literal / (47₁₀ / 57₈ / 2F₁₆)

tag>the literal text tag> (case sensitive)

.any character (except for line terminators)

<b>the literal text <b> (case sensitive)

Positive Lookahead(?=(?:(?!<\/?tag>).)*?\{1})

Non-Capturing Group(?:(?!<\/?tag>).)*?

*?repeats the group contents below any number of times:

Negative Lookahead(?!<\/?tag>)

<the literal < (60₁₀ / 74₈ / 3C₁₆)

\/?optionally matches the literal / (47₁₀ / 57₈ / 2F₁₆)

tag>the literal text tag> (case sensitive)

.any character (except for line terminators)

\{the literal { (123₁₀ / 173₈ / 7B₁₆)

1}the literal text 1}

Non-Capturing Group(?:(?!<\/?tag>).)*

*repeats the group contents below any number of times:

Negative Lookahead(?!<\/?tag>)

<the literal < (60₁₀ / 74₈ / 3C₁₆)

\/?optionally matches the literal / (47₁₀ / 57₈ / 2F₁₆)

tag>the literal text tag> (case sensitive)

.any character (except for line terminators)

<the literal < (60₁₀ / 74₈ / 3C₁₆)

\/the literal / (47₁₀ / 57₈ / 2F₁₆)

tag>the literal text tag> (case sensitive)

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.

Search reference

Regular Expression

<tag>(?=(?:(?!<\/?tag>).)*?<b>)(?=(?:(?!<\/?tag>).)*?\{1})(?:(?!<\/?tag>).)*<\/tag>

New

<tag><b>{1}test</tag>
<tag><b>test</tag>
<tag><b>{1}test</tag><tag><b>test</tag>
<tag>{1}test</tag><tag><b>test</tag>