== Why is this an issue?

include::../description.adoc[]


=== Noncompliant code example

[source,php]
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preg_replace("/start\w*?(end)?/", "x", "start123endstart456"); // Noncompliant. In contrast to what one would expect, the result is not "xx".
preg_match("/^\d*?$/", "123456789"); // Noncompliant. Matches the same as "/^\d*$/", but will backtrack in every position.
----


=== Compliant solution

[source,php]
----
preg_replace("/start\w*?(end|$)/", "x", "start123endstart456"); // Result is "xx".
preg_match("/^\d*$/", "123456789");
----