Part 01: Tutorial on lex/yacc
Why Stack Overflow recommends it
Stack Overflow users link it as a beginner reference when learning lex, whether to get a Lex program compiling, to check how rule matching works, or to follow along with a first example.
Recommended by 0 people across 0 different months, 2016 to 2020.
What it is
A 30-minute screencast by Jonathan Engelsma introducing lex/flex, the UNIX tokenizer generator. It gives a short intro to lexical analysis, walks through lex code examples, and shows how to integrate the generated tokenizer into a C program. It is part one of a two-part lex/yacc tutorial with source code on GitHub.
What people said
Cites darth vader · 2016-03 · Stack Overflow · on “flex output not showing correct behavior”
is there some reference for that? Because my professor just gave a breif explanation about how the first translation rule found will be used.This video : [this video] also says the same thing
Cites aitía · 2018-01 · Stack Overflow · on “Compiling a Lex program on OS X”
Is anyone able to better inform me on successfully compiling a Lex source file on OS X in terminal. I have written in HelloWorld.l the following: %% "hello world" printf("GOODBYE\n"); . ; %% Within the console I executed lex HelloWorld.l followed by gcc lex.yy.c -ll and ./a.out receiving a blank state within my window and no result. I am basing my knowledge on this topic from the source [1] [this video] and similar Stack question [2] [LINK] .
Cites Compeador · 2020-06 · Stack Overflow · on “Lex: expected expression before ‘[’ token when writing regular expressions”
I'm new to Lex [LINK] / Yacc [LINK] and am following this tutorial: Part 01: Tutorial on Lex/Yacc [this video] Here's my Lex file: %{ #include "main.h" #include <stdio.h> %} %% [a-zA-Z][_a-zA-Z0-9]* {return IDENTIFIER;} "&" {return RUN_DAEMON;} "|" {return SYM_PIPE;} ">" {return RED_STDOUT;} "<" {return RED_STDIN;} ">>" {return APP_STDOUT;} [ \t\n]+ {;} . {printf("unexpected character\n");} %% int yywrap(){ return 1; } However, after running the lex command, I try to compile lex.yy.c with gcc , but it spams me with this error: sbash.l: In function ‘yylex’: sbash.l:7:5: error: expected expression before ‘[’ token [a-zA-Z][_a-zA-Z0-9]* {return IDENTIFIER;} ^ sbash.l:7:6: error: ‘a’ undeclared (firs