Hebzuchtig versus lui

By default quantifiers are greedy: they consume as much as possible while keeping the pattern valid. Adding ? after a quantifier (*?, +?, ??, {n,m}?) gives you the lazy version: it consumes as little as possible.

Sample: <b>uno</b> e <i>due</i>

Greedy pattern  <.*>     matches:  <b>uno</b> e <i>due</i>   (everything)
Lazy pattern    <.*?>    matches:  <b>           </b>
                                   <i>           </i>        (4 matches with the g flag)

The exact same pattern, a single character of difference (? added to the quantifier), totally different results.

When it matters

• To extract the content between delimiters (HTML tags, quotes, parentheses) the lazy version is almost always the right one.
• To match up to end of line you usually want greedy (.*).

Greedy vs Lazy strategies in the engine

A greedy quantifier consumes as much text as possible and backtracks only if forced. By adding ? (lazy), the engine consumes the absolute minimum and advances one character at a time searching for the next match of the pattern.

Try it

Review exercise

Additional challenge