Lexical Analyser using Lex/Flex

Dev Shed Forums Sponsor:

December 10th, 2012, 03:14 PM

oussamaboun

Registered User

Join Date: Dec 2012

Posts: 10

Time spent in forums: 2 h 27 m 19 sec
Reputation Power: 0

Lexical Analyser using Lex/Flex

hello everyone

i need help from you

i want a Program to create Lexical Analyser for C Programming Language using Lex/Flex

thanks to you all

December 10th, 2012, 03:47 PM

Scorpions4ever

Banned ;)

Dev Shed God 9th Plane (9000 - 9499 posts)

Join Date: Nov 2001

Location: Woodland Hills, Los Angeles County, California, USA

Posts: 9,387

Time spent in forums: 1 Month 4 Weeks 1 Day 21 h 39 m 3 sec
Reputation Power: 4080

Code:

flex -P _my_prefix_ my_lex_file.l

What you put in my_lex_file.l depends on your requirements, which you haven't specified in your post.

__________________
Up the Irons
What Would Jimi Do? Smash amps. Burn guitar. Take the groupies home.
"Death Before Dishonour, my Friends!!" - Bruce D ickinson, Iron Maiden Aug 20, 2005 @ OzzFest
Down with Sharon Osbourne

December 10th, 2012, 04:49 PM

oussamaboun

Registered User

Join Date: Dec 2012

Posts: 10

Time spent in forums: 2 h 27 m 19 sec
Reputation Power: 0

i mean write a program using lex language that analyse a c programm and test every character and show its type if it is a digit or alpha or keyword like if or while or .... or special character i hope you understand what i meann... thanks for replying

December 11th, 2012, 12:10 AM

salem

Contributed User

Join Date: Jun 2005

Posts: 3,839

Folding Points: 153 Folding Title: Novice Folder

Time spent in forums: 2 Months 3 Weeks 2 Days 19 h 1 m 4 sec
Reputation Power: 1774

How about this
http://www.lysator.liu.se/c/ANSI-C-grammar-l.html

__________________
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper

December 11th, 2012, 06:53 AM

oussamaboun

Registered User

Join Date: Dec 2012

Posts: 10

Time spent in forums: 2 h 27 m 19 sec
Reputation Power: 0

thanks,it's not what i really mean but it helps me a lot .thanks again

December 11th, 2012, 09:33 AM

b49P23TIvg

Contributing User

Join Date: Aug 2011

Posts: 3,372

Time spent in forums: 1 Month 2 Weeks 3 Days 11 h 39 m 38 sec
Reputation Power: 383

beginnings of a php parser.

Attached is an (incomplete) php parser I just wrote (36 hours, including sleep.) It builds a parse tree and evaluates it. Handles integer variables, expressions, echo, if, string concatenation and some common operators. Not completely tested. Leaks memory. I'm not a php expert (not even a novice, I should say). (I DO know more about php than I knew last week.) The code sufficiently meets the rules of the task I was assigned.

Code:

  109   253  1814 z.y            (I used z.y to work out syntax tree execution.)
   19    77   543 00README.txt
   22    30   313 a.php
   61   174  1542 dictionary.c
    6     6    45 ex1.html
    6     6    45 ex1.php
    9    10    66 ex2.html
    9    13    83 ex2.php
    9    10    62 ex3.html
    9    13    79 ex3.php
    9    10    76 ex4.html
   11    13    93 ex4.php
   12    13    92 ex5.php
   16    18   173 example1.php
   21    24   266 example2.php
   73   206  1510 php2html.lex
  381  1252  9159 php2html.y
   27    70   374 test.sh
   21    42   353 tree.h
  830  2240 16688 total

Attached Files

php.zip (8.7 KB, 43 views)

__________________
[code]Code tags[/code] are essential for python code!

December 11th, 2012, 03:46 PM

oussamaboun

Registered User

Join Date: Dec 2012

Posts: 10

Time spent in forums: 2 h 27 m 19 sec
Reputation Power: 0

i found this one ...and this is what i mean thanks to everyone

letter [a-zA-Z]
digit[0-9]
%%
{digit}+("E"("+"|"-")?{digit}+)? printf("\n%s\tis real number",yytext);
{digit}+"."{digit}+("E"("+"|"-")?{digit}+)? printf("\n%s\t is floating pt no ",yytext);
"if"|"else"|"int"|"char"|"scanf"|"printf"|"switch"|"return"|"struct"|"do"|"while"|"void"|"for"|"float" printf("\n%s\t is keywords",yytext);
"\a"|"\\n"|"\\b"|"\t"|"\\t"|"\b"|"\\a" printf("\n%s\tis Escape sequences",yytext);
{letter}({letter}|{digit})* printf("\n%s\tis identifier",yytext);
"&&"|"<"|">"|"<="|">="|"="|"+"|"-"|"?"|"*"|"/"|"%"|"&"|"||" printf("\n%s\toperator ",yytext);
"{"|"}"|"["|"]"|"("|")"|"#"|"'"|"."|"\""|"\\"|";"|"," printf("\n%s\t is a special character",yytext);
"%d"|"%s"|"%c"|"%f"|"%e" printf("\n%s\tis a format specifier",yytext);
%%
int yywrap()
{
return 1;
}
int main(int argc,char *argv[])
{
yyin=fopen(argv[1],"r");
yylex();
fclose(yyin);
return 0;
}

Lexical Analyser using Lex/Flex

Developer Shed Advertisers and Affiliates