Description

flex is a tool for generating scanners: programs which recognized lexical patterns in text. flex reads the given input files, or its standard input if no file names are given, for a description of a scanner to generate. The description is in the form of pairs of regular expressions and C code, called rules. flex generates as output a C source file, 'lex.yy.c', which defines a routine 'yylex()'. This file is compiled and linked with the '-lfl' library to produce an executable. When the executable is run, it analyzes its input for occurrences of the regular expressions. Whenever it finds one, it executes the corresponding C code.

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