Regular expressions


In 1943, Warren McCulloch and Walter Pitts published a scientific paper, “The Logical Calculus of Ideas Underlying Nervous Activity,” in which they tried to understand brain function by modeling neurons. They didn’t know then that their work would have a huge impact on computer science.

In 1951, American mathematician Stephen Cole Claney, in his paper “Representation of Events in Neural Networks and Finite Automata,” proved McCulloch and Pitts’ ideas and formalized the definition of a “regular language” – a formal language that can be described by a regular expression.

A little later, in 1968, Ken Thomson (coauthor of Go, by the way) published “Regular Expression Search Algorithm.”

A regular expression is a pattern/pattern which defines the rules for finding (or replacing) a substring in a string.

Regular expressions can be used to:

Websites for checking and testing regular expressions:,

And to test your regular expression writing skills, I can advise:

Don’t forget two words of wisdom: “You have a problem. You decided to use regular expressions. Now you have two problems.” “When all you have is a Hammer, everything looks like a Nail”.

2020-06-13 Edit