Lex

Lex is a lexical analyzer generator used primarily in compiler construction and text processing. It reads a specification file containing regular expressions and corresponding actions, then generates C code for a scanner that tokenizes input streams. It is often paired with Yacc (Yet Another Compiler Compiler) for building parsers in language development.

Also known as: Flex, lexical analyzer generator, lex scanner generator, lex tool, lexical analysis tool

Why learn Lex?

Developers should learn Lex when building compilers, interpreters, or tools that require lexical analysis, such as syntax highlighters, configuration file parsers, or data validation systems. It automates the creation of efficient tokenizers, reducing manual coding errors and speeding up development in projects involving structured text processing.

Learning Resources

• tutorial: Lex & Yacc Tutorial
• docs: GNU Flex Manual
• book: Lex and Yacc - O'Reilly Book
• tutorial: Compiler Construction Using Flex and Bison