The ’.’ isn’t working the way I expected.

Here are some tips for using ‘.’:

• A common mistake is to place the grouping parenthesis AFTER an operator, when you really meant to place the parenthesis BEFORE the operator, e.g., you probably want this (foo|bar)+ and NOT this (foo|bar+).

  The first pattern matches the words ‘foo’ or ‘bar’ any number of times, e.g., it matches the text ‘barfoofoobarfoo’. The second pattern matches a single instance of foo or a single instance of bar followed by one or more ‘r’s, e.g., it matches the text barrrr .

• A ‘.’ inside ‘[]’’s just means a literal‘.’ (period), and NOT “any character except newline”.
• Remember that ‘.’ matches any character EXCEPT ‘\n’ (and ‘EOF’). If you really want to match ANY character, including newlines, then use (.|\n) Beware that the regex (.|\n)+ will match your entire input!
• Finally, if you want to match a literal ‘.’ (a period), then use ‘[.]’ or ‘"."’