of operation work on some other string. The right argument is a search
pattern, substitution, or transliteration. The left argument is what is
supposed to be searched, substituted, or transliterated instead of the default
-$_. The return value indicates the success of the operation. (If the
+$_. The return value indicates the success of the operation. If the
right argument is an expression rather than a search pattern,
substitution, or transliteration, it is interpreted as a search pattern at run
-time. This can be is less efficient than an explicit search, because the
-pattern must be compiled every time the expression is evaluated).
+time. This can be less efficient than an explicit search, because the
+pattern must be compiled every time the expression is evaluated.
Binary "!~" is just like "=~" except the return value is negated in
the logical sense.