Character classes in regular expressions are a convenient way to match one of several possible characters by listing the allowed characters or
ranges of characters. If a character class contains only one character, the effect is the same as just writing the character without a character
class.
Thus, having only one character in a character class is usually a simple oversight that remained after removing other characters of the class.
Noncompliant code example
"a[b]c"
"[\\^]"
Compliant solution
"abc"
"\\^"
"a[*]c" // Compliant, see Exceptions
Exceptions
This rule does not raise when the character inside the class is a metacharacter. This notation is sometimes used to avoid escaping (e.g.,
[.]{3} to match three dots).
