What is another term for regular expressions?
A regular expression (shortened as regex or regexp; also referred to as rational expression) is a sequence of characters that specifies a search pattern.
What is regular expression and its properties?
It is a way of representing regular languages. They can define the same language that various forms of finite automata can describe. Regular expressions offer something that finite automata do not, i.e. it is a declarative way to express the strings that we want to accept.
How to find a comment in a regular expression?
This seems the natural way to do it. /\\* finds the start of the comment (note that the literal * needs to be escaped because * has a special meaning in regular expressions), .* finds any number of any character, and \\*/ finds the end of the expression. The first problem with this approach is that .* does not match new lines.
Are there any regular expressions that match too much?
This can be overcome easily by replacing the . with [^] (in some regular expression packages) or more generally with (.| [ ]): This reveals a second, more serious, problem—the expression matches too much. Regular expressions are greedy, they take in as much as they can. Consider the case in which your file has two comments.
Which is the correct way to use a regular expression?
When first attempting this problem, most people consider the regular expression: /\\*.*\\*/ This seems the natural way to do it. /\\* finds the start of the comment (note that the literal * needs to be escaped because * has a special meaning in regular expressions), .* finds any number of any character, and \\*/ finds the end of the expression.
How are regular expressions used in pattern matching?
A regular expression (sometimes called a rational expression) is a sequence of characters that define a search pattern, mainly for use in pattern matching with strings, or string matching, i.e. “find and replace”-like operations.