These topics introduce the concept of regular expressions and explain how to create and use them.
A regular expression describes one or more strings to match when you search a body of text. The expression serves as character pattern to compare with the text being searched. You can use regular expressions to search for patterns in a string, replace text, and extract substrings.
Explains how to specify that a pattern that you are searching for has to appear either at the start or end of the searched string, or the start or end of a line or word in the searched string.