An atom followed by plus matches a sequence of one or more matches of the atom. An atom followed by a question mark matches a match of the atom, or the null string. It normally matches any single character from the sequence. How to Use Regular Expressions Regular expressions are strings used for matching. Most people are used to wildcard matching from the command lines of many operating systems.
Regular expressions are different.
However, this is still not equivalent to the wildcard search. This is actually applicable in regular expressions to a point. In the example, the asterisk is preceded with a period, which means none, one, or more of any character. When you use a plus, it means one or more of the previous characters in the pattern. Table C-1 shows a comparison of matches.