Question

Define regular expression.

Answer 1

a sequence of symbols and characters expressing a string or pattern to be searched for within a longer piece of text.

Answer 2

A regular expression is a special text string for describing a search pattern. You can think of regular expressions as wildcards on steroids. You are probably familiar with wildcard notations such as *.txt to find all text files in a file manager. The regex equivalent is .*\.txt.

. For example, the Hello World regex matches the "Hello World" string. . (dot) is another example for a regular expression. A dot matches any single character; it would match, for example, "a" or "1"