What is regular expression?
A regular expression is a pattern that the regular expression engine attempts to match in input text. A pattern consists of one or more character literals, operators, or constructs.
Below is an instruction that describes a task. Write a response that appropriately completes the request. ### Instruction: What is regular expression? ### Response: A regular expression is a pattern that the regular expression engine attempts to match in input text. A pattern consists of one or more character literals, operators, or constructs. 