# "[^"]*"  ## Metadata - Author: [[princeton.edu]] - Full Title: "[^"]*" - Category: #articles - Summary: This section introduces formal languages, strings, and alphabets. Regular languages are defined and can be specified by regular expressions (union, concatenation, closure) or recognized by DFAs and NFAs. Many examples and exercises show practical use, including Java's matches() and pattern-building problems. - URL: https://introcs.cs.princeton.edu/java/51language/ ## Highlights - Basic definitions.We begin with some important definitions. • A *symbol* is our basic building block, typically a character or a digit. • An *alphabet* is a finite set of symbols. • A *string* is a finite sequence of alphabet symbols. • A *formal language* is a set of strings (possibly infinite), all over the same alphabet. ([View Highlight](https://read.readwise.io/read/01k43k89habtgfsr5v3wxvrr8n))