A regular expression, also known as a regex or regexp, is a string whose pattern (template) describes a set of strings. The pattern determines which strings belong to the set.

Regular expressions 101 Let’s start simple. Suppose you want to search for a string with the word “cat” in it; your regular expression would simply be “cat”.

Using RegEx in your code requires the RegEx object, located within the System.Text.RegularExpressions namespace. For a usage example, see Listing 1 below. The code in this example reads a string as ...

But grep isn’t the only program that uses regular expressions. Awk, sed, Perl, editors like VIM and emacs, and many other programs can use regular expressions for pattern matching.

The real strength of regular expressions however, lies in the handling of repetition. To illustrate this let’s take the example of needing to determine if a string contains a valid phone number.

Perhaps regular expression parsing is slower than string manipulation; I didn't run any performance analysis on the code samples presented here. But even if the regex-based code is a tad slower, the ...

Pattern Matching Using Regular Expression (RX) Functions and CALL Routines You can use a special group of functions and CALL routines to match or change data according to a specific pattern that you ...

Rubular Link Granted, that single line RegEx looks like a random garble of characters at first glance. In reality, it is a carefully constructed set of rules to dictate a pattern match on a string.

Regular expressions is a sequence of characters that define a search pattern. Usually such patterns are used by string searching algorithms for “find” or “find and replace” operations on ...

If you work with text, you owe it to yourself to learn regular expressions, and Patterns can help you do that--as well as figure out exactly what your search patterns are capturing.