When an alternation contains multiple alternatives that consist of a single character, it can be rewritten as a character class. This should be preferred because it is more efficient.

Noncompliant Code Example

preg_match("/a|b|c/", $str); // Noncompliant

Compliant Solution

preg_match("/[abc]/", $str);
// or
preg_match("/[a-c]/", $str);