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Flex for Windows- Lex and Yacc(Bison) Installer for Windows 7/8.1/10 32-bit & 64-bit


Hello friends, recently we were introduced to lex and yacc parsers in our syllabus, but the introduction to lex and yacc [flex and bison] was made in linux environment . Personally, I didn’t felt necessary to Install the Complete Linux OS on my Laptop just because to have gcc/lex/yacc libraries which are a mere 30 MB size , and to allocate 10GB Disk Space + RAM[in Virtual Machine] to Linux is something which i am not very Fond of :( . After searching on Sourceforge, I came across the MinGW [ Win 32 Port of cc/gcc/g++] and the GNU-Win32 ports of flex[lex] and bison[yacc] respectively. So in order to make it easy to use and install i Packaged all of them into a single one click installer – Flex for Windows 7/8/10

Contents / Salient Features of Flex Windows

  • In-built GCC/G++/cc Libraries of LinuxThe Flex Windows Package contains inbuilt Gcc And g++ libraries [c and c++ compilers] which are ported to windows officially by MinGW and are actively developed by the Linux Open Source Community
  • Lex and Yacc Package Binaries  :  The package contains the latest updated versions of Lex and yacc binaries [flex and bison] which are developed by their developers . The original binaries are included as-it-is in the package so as to ensure smooth and error free compilation and build of your Programs.
  • Pre-Configured EditPlus IDEThe package also contains EditPlus IDE which contains pre-defined Blank templates for the Lex/Yacc/C/C++/Java Files, thus each time you want to type a program you can simply use the New Lex / New Yacc template, and the basic code will be inserted thus saving your time and efforts to type :P.
  • The EditPlus IDE also contains user Commands for Lex Compile,Yacc Compile,Lex Build , Lex+Yacc Build, Band for Execute. thus, saving your time to type complete commands like “lex abc.l” or cc lex.yy.c  y.tab.c -o <object file>” blah blah..” you can simply click the Buttons according to the function you wanna perform and the command will be executed, the command itself will insert the filename,parameters etc :) Amazing! isn’t it ? And to top it off the IDE will capture the command output , errors if any will be shown in the IDE window itself ,thus you can easily change the code,save and compile in split seconds making it easy and pretty much like Geany/Eclipse/Netbeans :)
  • If it still doesn’t impress you , you still can open CMD and compile and build the hard-old-fashioned way :)
  • No need to Set PATH variables , the PATH variables , for the gcc/lex/yacc are added by the installer itself, thus saving the efforts required to set PATH :)
  • Single installer , works on all version of Windows., here’s a Snapshot of the Flex for Windows in Action

Download : Click here to download Flex for Windows 7/8/8.1/10/XP 32-bit || 64-bit

Download Mirror #1 :  Click here to download Flex for Windows 7/8/8.1/10/XP 32-bit || 64-bit from Mirror # 1

Update : For those who are facing errors with Bison/yacc Package in Flex for Windows can also install Lex/Yacc on Ubuntu/LinuxMint easily by referrig this article.

Cautions/Precautions to be taken :

  • Make Sure you install the Package in any folder except “Program Files” / “Program Files (x86)” The Package won’t work if installed in Program Files.
  • The Windows Lex Version requires “%option noyywrap” ,  Please make sure this option is present , before you compile Programs.
  • The “-ll” and “-ly” arguments won’t work in Windows as they are not required in Windows Environments.
  • If the IDE Lags/Code doesn’t respond on compile command , Please re-run the FlexIDE as “Run as Administrator” .

Method to Run Programs through IDE

  • Some users have reported difficulty using the package for running the programs or giving the inputs, hence we are simplifying the instructions to run the programs below. In some cases you may find that the program terminates after executing after getting inouts from console if compiled and executed through IDE, In such cases the CMD way is recommended for executing .

Case 1 : Only lex Programs need to be run and built and executed

  • Click the compile lex button in the IDE.
  • Click the build lex button.
  • Click on Execute .

Alternate way through CMD 

  • Click on Execute CMD directly button in the IDE.
  • Compile the Lex File by typing the command lex <filename>.l
  • Build the Lex File by gcc/cc command in the CMD e.g gcc lex.yy.c -o <executable name for program>
  • Execute the program by typing <executable name for the program>.exe
  • The -o <executable name for program>  parameter is optional, you can skip the said parameter by directly building by gcc lex.yy.c
    and then directly execute your program by typing a.exe

Case 2 : Both Lex and Yacc Programs together have to be linked and Compiled – Executed

  • Compile the yacc program by the compile yacc button from the IDE.
  • Compile the Lex program by compile lex button.
  • Build the program by clicking the “lex-yacc” build button.
  • Click on Execute button.

Alternate way through CMD

  • Click on the Execute CMD button in the IDE.
  • Compile Yacc file by typing command yacc -dy <filename.y>
  • Compile the Lex File by typing the command lex <filename>.l
  • Build the Lex File by gcc/cc command in the CMD e.g gcc lex.yy.c y.tab.c -o <executable name for program>
  • Execute the program by typing <executable name for the program>.exe
  • The -o <executable name for program>  parameter is optional, you can skip the said parameter by directly building by gcc lex.yy.c y.tab.c
    and then directly execute your program by typing a.exe

The binaries are provided as it is , so they cannot contain any errors, However if you face any errors/problems while installing or running, do comment :) we will try to solve it . If you have any doubts/suggestions do leave them behind in comments :)

UPDATE : All yacc fixed in this new version — New Update to sequence for Activations by Maria —

“select the name.l -> click on Lex Compile -> click on Lex Build ->
-> select name.y -> click on Yacc Compile – click on Lex + Yacc Build ->
-> click Execute exe directly or Open CMD (typing the name)”


  1. divya July 14, 2014

    how to give inputs?
    where to find outputs?
    show a demo

    1. Chaitanya July 15, 2014

      inputs can be given through files or through consle as per your wish , the normal method of using fopen(“filename”,”r”); will work, same is the case with outputs , we can write the outputs on the file .

  2. divya July 14, 2014

    please its urgent

    1. Chaitanya July 15, 2014

      and for giving inputs through the console we can directly give the commands after compiling the yacc, then the lex programs , then building using the lex-yacc build , and then by executing it . it would be better if you can share your program then we can guide you on the exact way . Thanks

    2. Chaitanya July 15, 2014

      We have added the execution instructions to the post, hope they will help 🙂 . do report if you still encounter problems , Thanks!

  3. Shasan August 26, 2014

    mai pehle bohot nirash rehta tha, bohot hatash rehta tha.
    College me ubuntu pe lex and yacc k programs sikha rahe the
    mujhe ubuntu me lex yacc gcc install karne me prob ho rahi thi
    mai dukhi rehne laga.
    mujhe coding karne k kide ne pareshan kar rakha tha
    maine kai upaay apnay par mujhe nirasha hi haath lagi
    maine windows pe flex and bison khud install karne ki sochi
    usme bhi mujhe nakabyabi mili

    Lekin phir mujhe techapple ka single-installer flex mila
    ab mai kya batau mai kitna khush rehne laga hu
    meri to duniya hi badal gai hai
    yacc or lex apne ghar pe bhi run kar paa raha hu
    mera coding ka kida bhi bohot khush hai
    meri girlfriend bhi mujhse bohot khush rehne lagi hai*
    mere nagar sevak bhi mujhse bohot khush hai
    meri gali ka kutta bhi ap mujhpe gusse se nahi bhonkta
    or ye sab techapple ki wajah se hua
    mai apne sab dosto ko ye recommend karunga
    THAANNKK you techapple

    *girlfriend ki khushi ka kuch or karan hai
    wo isliye khush hai kyu k
    ***censored*** 😛

    1. Chaitanya August 29, 2014

      Thank you so much hasan 🙂

  4. Ashmita August 28, 2014

    plz can you elaborate on how to give inputs?where is the exe file stored?
    can you plz giv one demo…plz reply its urgent.

    1. Chaitanya August 29, 2014

      Sorry for the delay in my reply 🙁 , actually the exe d\file is stored in the same folder where the lex and yacc files are stored (the folder in which you are saving the programs) .
      I will be making a demo video soon..
      till then you can read the following quote to execute instructions,–

      “Click on the Execute CMD button in the IDE.
      Compile Yacc file by typing command yacc -dy
      Compile the Lex File by typing the command lex .l
      Build the Lex File by gcc/cc command in the CMD e.g gcc lex.yy.c y.tab.c -o
      Execute the program by typing
      The -o
      parameter is optional, you can skip the said parameter by directly building by gcc lex.yy.c y.tab.c
      and then directly execute your program by typing a.exe”

      once you execute the a.exe or program exe through the command prompts you can give input there itself.. in the command prompt window 🙂

      1. ashmita August 30, 2014

        i have already tried above steps..
        My lex program was first saved outside the directory so while compiling that using lex filename.l, it use to give an error “lex not recognized as internal or external command”…after this i saved my program inside lex folder where lex is installed…then that error was gone
        but now it gives an error “gcc not recognized as internal or external command” i even tried changing path from “Advance System properties” but still it is giving same error.
        I have given the path where my lex is installed is that correct??

        1. Chaitanya August 30, 2014

          Okay. So we need to add the environment variables for gcc and lexx bin folder to path variable,or advanced system properties.. Or I can create an batch file for the same if required..

          1. Ashmita August 31, 2014

            i m not able to sort it out…
            i have tried everything..i have even added environment variables for gcc,lex and bison bin folder to path variables.. still it is not working..plz provide me the batch file if possible..plz…

          2. Chaitanya August 31, 2014

            Okay , am extremely sorry for the inconvenience caused :(, creating the batch file will upload it by tomorrow evening in this post, thank you for using our product.

          3. Chaitanya September 1, 2014

            Can you give us the installation directory where you have installed the package ? we require it for adding it to the batch file, else its already ready to be executed 🙂
            Here’s the alternative solution Please download both these files and extract them to the “C:\” drive
            1st file – http://goo.gl/5RY1nL
            2nd file – http://goo.gl/XcwNi3
            Now after you have extracted please go to c:\flex activator and execute the activator.exe and please do not close the activator window, let it remain open, now execute the flex windows IDE from the Desktop 🙂 It will run without any hiccups 🙂

          4. Ashmita September 1, 2014

            Thanks a lot.its working…
            i m very very thankful to u..
            thank u..

          5. Chaitanya September 1, 2014

            You’re welcome Ashmita 🙂 glad, it finally worked for you 🙂

  5. harshamaddula September 21, 2014

    Its showing cannot create process error when i am trying to compile the code

    1. Chaitanya September 21, 2014

      @harshamadulla, is the same error ocurring when you are trying to compile through the CMD?

  6. Bavith September 30, 2014

    no comments.. this is simply a time waste.. i cant work in my windows 98

    1. Chaitanya September 30, 2014

      It won’t work in Windows 98 🙁 you’ll have to compile and build manually through MS-DOS Prompt as Windows 98 is DOS based 🙁

      1. skitija October 1, 2014

        only a fool can ask lex and yacc for windows 98.. get up to date with d world bro.. u r more than 15 years in d past 😉

        1. Makhilesh October 1, 2014

          Seems like somebody has forgotten his professional ethics!!

      2. Nisha October 4, 2014

        Lex is properly running in CMD but yacc programs are not running please help me soon.It gives me error for y.tab.h.It does not create it..

        1. Chaitanya October 4, 2014

          Please run the program through command and add the option -d to the yacc command 🙂

    2. Makhilesh October 1, 2014

      A 3rd year CS engineering student’s question?
      Never expected this from you.

    3. Makhilesh October 1, 2014

      I would like to sponsor a new laptop to you:)
      Come to Vana Vihara tommorrow:P

  7. manisha October 1, 2014

    what you people are talking? By the by, what is lex and yacc?? why it is used? which games are those? i play only throwball.. That also we won because our opponents dint come:-)

  8. manisha October 1, 2014

    even i need free laptops. i like red colour.. so get me red colour laptop ok.. DELL i dont like because battery not good.. ok bye guys.. i have to write assignments.. also i have to write dbms imposition 4 times.. happy dussera to all..

    1. Akhilesh Acharya October 1, 2014

      Is HP laptop fine?
      now bye..
      I have to write dbms imposition(5 times) ,OS assignment,SS Assignmeent and SS notes.
      Also FLAT homework….
      Happy dussera to you manisha:)
      going to miss u for next 5 days:(:(

      1. Manisha October 3, 2014

        I am sorry.
        I meant Happy Dussehra to all.
        Mr.Akhilesh Acharya, you really need English lessons.

  9. Akhilesh October 1, 2014

    I have only heard of C program.
    How to execute c programs in lex and yacc???

  10. manisha October 1, 2014

    why you want lex and yacc to execute c program.. u r really stupid.. go and download turbo C.. its better than these things..dont disturb me.. i have to prepare presentation on nano technology in mars..

  11. Akhilesh Acharya October 1, 2014

    Forget c program…
    suggest me a seminar topic too….
    if i dont get any topic then i’ll give seminar on Moral values and Professional ethics…
    it feels great to listen to moral science class right?
    By the way my team needs 2 more members….plz give us our ‘lion'(i mean lano) back…

  12. ForgiveUs October 1, 2014

    Dear Chaitanya,

    A sincere sorry for the stupidity shown by the above few people.They didn’t mean to disturb you.
    They were just playing pranks on each other.I hope you didn’t mind it.

    Your software is really a boon for us.


    1. Chaitanya October 2, 2014

      No issue mate 🙂
      I too enjoyed this non tech conversation 🙂 being a final year engineering student am aware of all these pranks 😛
      Thank you for using the software 🙂 keep visiting 🙂

      1. Makhilesh October 6, 2014

        keep visiting???
        Does that mean you don’t mind us using this site for non-technical conversation?

        1. Chaitanya October 6, 2014

          Nope I don’t mind it, we have our freedom of speech and expression so this site too is a platform for the same 🙂

  13. Makhilesh October 3, 2014

    Had a very good time doing vihara in vana at “Vana Vihara” yesterday…….:)
    Feeling very proud of myself for sponsoring laptops….:)
    All thanks to techapple.net:)

  14. manisha October 3, 2014

    you dont have any other work idiot?

  15. Makhilesh October 3, 2014

    Stop calling me an idiot,you silly little..
    I was so happy yesterday at vana vihara yesterday that i wanted to share it…
    by the way why are you concerned????Is it because i am not thanking you???
    Are you jealous:P

  16. manisha October 3, 2014

    full jelos.. who telled u talk rubbish here..? english learn from me. u jealos of suppper english of main(mine).. meen maaruna mone ninna stupid..

  17. Manisha October 3, 2014

    You expect me to learn English from you???
    First learn the spelling of grammer(I mean grammar)..
    suruku ninna mone thula…i hope you have a mirror…

  18. kshithija October 3, 2014

    sorry manisha.. it was me pranking.. ill learn from my mistakes.. everythings fine 🙂 b happy..

  19. Manisha October 3, 2014

    Its okay….
    Thanks for your comments about Makhilesh…
    I think he deserves it..
    I don’t think he has a mirror(because he lost all his money sponsoring laptops at Vana Vihara)…
    We better gift him one..

  20. Kshithija October 3, 2014

    I doubt if anyone has taken laptops that he sponsored.
    All PCs had Windows 98 installed in it..

  21. mankishaa October 3, 2014

    pehle me bahut kush tha.. baad me techapple pe me ne flex and yacc ki page dekhi.. waha par comment dek kar meri kushi chali gayi. ab aisa lag raha he ki me koi sulsaan shamsaan ke beech ek chudail ke kaala jaadu me band ho gaya hu.. muje koi bacchhhaoo….

    1. Manisha October 3, 2014

      kisne kaha tha is page mein comment karne ke..wo bhi class ke waqt…
      chup chap download karke wapas jaana chaiye tha..

  22. Makhilesh October 3, 2014

    Issi liye main tuje “Vana Vihara” mein bhula raha tha….
    bahut hi accha jaga hai…
    hare bhare ped hain,titliyaan hai,aur kya kya nahi …
    phir bhi bore ho gayi tho Windows 98 installed PC hain na…
    usme c program kya ethical hacking aur android app develop bhi kar sakthe hain…

  23. Makhilesh October 3, 2014

    Okay now bye guys…..
    got to sleep…
    have some renovation work at vana vihara tomorrow..so i need to wake up early tomorrow…
    also OS assignment and dbms imposition(only once did i finish,4 more times to write) has to completed you see..
    Once again wish you all a very happy dussera (i mean Dussehra):-)
    Thank you Manisha for correcting me.If I had used this spelling in class then all my freinds would have made fun of me.You know right,I don’t like to be the source of entertainment in class…
    Once again thanks a lot

  24. mankishaa October 5, 2014

    Haste rahiye, muskurate rahiye, aurato ka izzat kariye, praaniyo se pyaar kariye aur dekte rahiye Windows 98 ki jaaadoo!!! 😉

    1. Chaitanya October 6, 2014

      Lol this one was from comedy nights with Kapil 🙂

      1. Makhilesh October 6, 2014

        Dedicated to techapple.net

        Jise zindagi dhoondh rahi hai
        Kya ye woh makaam mera hai
        Yahaan chain se bas ruk jaaun
        Kyun dil ye mujhe kehta hai
        Jazbaat naye se mile hain
        Jaane kya asar ye huaa hai
        Ik aas mili phir mujhko
        Jo qubool kisi ne kiya hai

        Kisi shaayar ki ghazal
        Jo de rooh ko sukoon ke pal
        Koi mujhko yun mila hai
        Jaise banjaare ko ghar
        Naye mausam ki sehar
        Yaa sard mein dopahar
        Koi mujhko yun mila hai
        Jaise banjare ko ghar

        Now don’t that this one is from Ek Villain

        1. Chaitanya October 6, 2014

          Wah wah actually the ek villain guys copied your song 🙂 you should sue them with a copyright case :p

          1. Makhilesh October 6, 2014

            I would have.
            But i am in short of cash…invested all on renovating vana vihara 🙁

    2. Makhilesh October 6, 2014

      Sorry… I don’t watch Comedy nights with Kapil…..
      I watch only Shastri Sisters, Pavithra Rishta, Suhani si ek ladki, Is pyaar ko kya naam doon,laut aao trisha and Pyaar ka dard hai…..superb daily soaps…..do watch them….
      Also CID….”Darwaza thod do Daya”

  25. Makhilesh October 6, 2014

    Cannot compile yacc programs.
    y.tab.c and y.tab.h file are not created while compiling.
    m4_define errors are obtained.

    1. Chaitanya October 6, 2014

      Please ensure you compile through cmd with – d flag to get the header file:)

      1. Makhilesh October 6, 2014

        I have used -d option while compiling…..but of no use….
        whole page is filled with errors…something like m4_define errors…
        is it necessary to have both yacc.exe and lex.exe in the same folder

        1. Chaitanya October 6, 2014

          Nope it isn’t necessary to keep them in the same folder 🙁 actually it’s because of the program code incompatibility 🙁 I will highly recommend if you can get the same code running in Linux bison to copy the header file from there or you can try to install lex and yacc on Ubuntu it isn’t a big deal 🙂 for cse guys ”;)

          1. Makhilesh October 6, 2014

            Ubuntu par baadh mein try karenge…..
            First say how to solve this problem in Windows 8…..
            If you don’t know seedhe seedhe bhol na 😛
            Itna bada paragraph likha…..phir bhi solution nahi hai….
            And we know that we are cse guys no need to stress:P

          2. Chaitanya October 7, 2014

            Fixed in the new version :), Please uninstall any existing flex version and install the new version from the download links 🙂
            I know but mere exams chal rahe the isliye was trying to postpone the update 😛

  26. Indhushree K October 7, 2014

    Happy Birthday Makhilesh 🙂

    Words of wisdom:
    “Laugh when you still have teeth”
    🙂 🙂 😛

  27. Indhushree K October 7, 2014

    Cannot compile yacc programs.
    y.tab.c and y.tab.h file are not created while compiling.
    m4_define errors are obtained.

    1. Chaitanya October 7, 2014

      Fixed in the new version :), Please uninstall any existing flex version and install the new version from the download links 🙂 , Thanks for reporting the issue,,

  28. mankishaa October 11, 2014

    i have exams from monday.. but i also have 16 somvaar vrat at siddi vinayaka temple.. wat shud i do?? shud i write exams or shud i go to temple??

    1. Chaitanya October 11, 2014

      better you go to a cafetaria 😛 atleast that would be a unique experience 🙂

  29. mankishaa October 12, 2014

    thnx 4 d advice.. aapke idea ne dimag ki batti jalaa di 🙂

    1. Chaitanya October 13, 2014

      Welcome , hope you had great exams and time at cafeteria 😛

  30. vivek aiyer October 15, 2014

    hey when i type gcc lex.yy.c y.tab.c a list of errors are coimg wat to do plz help me urgently

  31. Ahmad Kadi October 20, 2014

    I would like to ask the following, please answer me.
    i followed the instruction in case 1
    after i pressed the execute button
    a window like cmd appeared without any characters, where should i insert the input file after that??

    1. Ahmad Kadi October 20, 2014

      i solve it thank you
      what i have to do is to write test lexemes
      and the program will recognize it and execute the corresponding action
      and the print action will appear in the window

  32. Paul Yang October 31, 2014

    I like EditPlus IDE. Now I want to recompile source file (flexded.h) to increase variable MAXIMUM_MNS, I would like to get your advice ASAP. I know how to do this in Linux, but not in Windows.



    1. Chaitanya October 31, 2014

      Thank you Paul for using the software 🙂 though I haven’t tried it in Windows you can directly edit the header file and recompile it using gcc from mingw in Windows, I will recommend copying the edited header file from Linux into Windows, and the compiling it in Windows .

  33. Paul Yang October 31, 2014

    Thank you very much, Chaitanya.

    I downloaded the flex source code from http://gnuwin32.sourceforge.net/packages/flex.htm which has
    file flexdef.h. In Linux, I run “./configure”, “make” and “make install”. The revised variable MAXIMUM_MNS will take effect. But in windows EditPlus IDE, I could not find file flexdef.h. Would you
    please recompile the whole package in your computer, then show me the procedure in details (I don’t
    know how to run command “./configure”, “make” “make install” in Windows.

    Best regards,


    1. Chaitanya November 1, 2014

      sure, I can show you the complete procedure but its not possible for me until 14th As my exams are going on 🙁
      in the mean time you can search On Google for running make command On Windows it’s simple!

  34. unknown November 28, 2014

    lab exams are over.. nw i don find any use of ur software..

    1. Chaitanya November 28, 2014

      lol 😀 😛 , you can use it to type the lyrics of your favourite songs 😉

  35. Makhilesh March 24, 2015

    Give me the OpenGL code for drawing the loading symbol (progress ring) used in windows 8, 8.1 or 10.

  36. give me an example plis!!!! y just read tutoprials for linux in terminal , but i dont understand how to use the ide

  37. raj August 25, 2015

    File is not present in link to download…so now how can i download it…?

  38. ranjan aryal September 20, 2015

    I need this software for 64 bit. there is problem in download. how can i download it ??

    1. Chaitanya September 20, 2015

      Hello Ranjan, looking into the links.. Shall provide another download mirror if required 🙂

  39. ritu November 29, 2015

    hi…listen when i want to execute a file it asks me the name of executable filename…where do i find the name..??
    is it the same name as the filename i created..??
    and also i cant use int yywrap function here..??

    1. ritu November 29, 2015


    2. Chaitanya November 29, 2015

      Hi Ritu, you can find the executable in the samw folder where the lex yacc file is saved.. You can use the ya wrap function in yacc file..

  40. ေန လင္း January 18, 2016

    . When i click lex file compile and lex build , all ok. But unfortunately when i click in “Execute exe directly” cmd is not work and show as this follow. Please help me. What can i repair this error. This need to type scanner.exe,because of my lex file is scanner.l . But i don’t know where i can type this word”scanner.exe”. Please help me anybody.Thanks you .

    Volume in drive C has no label.
    Volume Serial Number is 3B2F-ED60

    Directory of C:\Users\Administrator\Desktop\lex

    01/18/2016 05:17 PM .
    01/18/2016 05:17 PM ..
    01/18/2016 06:05 PM 142,535 lex.yy.c
    01/18/2016 05:15 PM 105 Noname1.cpp
    01/18/2016 05:09 PM 27,338 scanner.l
    3 File(s) 169,978 bytes
    2 Dir(s) 14,670,237,696 bytes free
    Please enter the .exe of the Compiled File Name you want to execute
    ‘explorer.exe’ is not recognized as an internal or external command,
    operable program or batch file.
    Press any key to continue . . .

  41. muthu1712 April 23, 2016

    I’m unable to download the file. Clicking on the download link shows no response. please help me out as soon as possible. I have exams upcoming next week

  42. Fabiano August 9, 2016

    Broken link. :/

  43. Mamatha September 13, 2016

    Im not able to download this flex package.. can anyone send the link.?

  44. Zayn September 28, 2016

    Unabe to download
    Download link is broken
    Plz re upload it.

  45. Aditya Mehra February 5, 2017

    it just says eof encountered inside an action when i compile it

  46. maham March 13, 2017

    i want a registeration code … if possible then please tell me.

  47. rupal April 13, 2017

    hello sir
    i download this package n install it successfully
    only problem is that when i follow the steps of execution in case 1 or 2 for CMD, it gives error for last step (i.e. Execute the program by typing .exe)
    the error is p.exe is not recognized as internal or external command, operable program or batch file
    plz help its urgent …..

  48. Nattiya April 14, 2017

    When I try to compile,it says commandprompt.bat is not recognized as an internal and external command, operable program or batch file. I added C:\Windows\System32 as path in my environmental variables. It still says it is not recognized.

    How to sort this out? help please

  49. Rufus April 25, 2017

    Greetings to you all,
    The download link to the application is broken. Is there any way to upload a new link to the IDE or reactivate the current one? Response will be highly appreciated.

    1. Chaitanya April 25, 2017

      Hi Rufus,

      Thank you for bringing to our notice , we have fixed the broken links and updated the article with the new ones 🙂 . Please try downloading using the new links. Thanks!

  50. Neelima Lalwani May 2, 2017

    The links that you have uploaded on Dropbox(activator.exe…) to resolve the error ‘Lex’ is not recognised as an internal or external command… , dont work. It directs me to the dropbox page that says the link has been temporarily disabled due to traffic on this account
    Please help.

    1. Neelima Lalwani May 2, 2017

      * disabled due to the traffic created by the account’s links.

  51. farhankarim May 8, 2017


    Hi i am trying to compile code from lex and yacc book by John R. Levine
    in the book the instructions for compiling are for unix below

    We called our various lexers chl-N.l, where TVcorresponded to a particular
    lex specification example. Similarly, we called our parsers chl-M.y, where
    again Mis the number of an example. Then, to build the output, we did the
    following in UNIX:

    lex chl- n.l
    yacc -d chl- m.y
    cc -c lex.yy.c y.tab.c
    cc -o example- m. n lex.yy.o y.tab.o -11
    which obviously won’t work.

    The .l file has no main function and .y has main function when i try to compile the .l file it gives error of winmain [email protected] is there any workaround for it using EditPlus IDE??
    please reply soon
    I have windows 10(64-bit) i have installed flex,bison,and trying to compile through ide
    the code link is below
    i am trying to compile files ch1-06.l ch1-06y ch1-06.h in prog.zip provided with book.

  52. shoeb August 8, 2017

    I have problem in execute exe directly.
    it syas ,
    explorer.exe’ is not recognized as an internal or external command,

    how can i solve this.

  53. Avnish Anand November 2, 2017

    after compiling .l or .y file i am getting a promt “cannot create process”

  54. Marko March 25, 2018

    Hi! I’d like to read an external txt file. How can I do? I ve tried in the yacc file this but it’s not working. Thanks!

    int main(void) {

    extern FILE *yyin;
    yyin = fopen(“file.txt”, “r”);

    if (yyin != NULL) {
    } else {
    printf(“Not opened”);

  55. Ganesh A January 13, 2020

    i have used two users. first user right admin and second user right is users. i have execute the program in admin user but cannot be run in users

  56. Ove April 19, 2020

    How old is this version? I.m trying to generate a c++ class, but the Flexlexer.h file is using the old CFront iostream library (#include ). In addition at least 3 files are missing according to the documentation, all related to input from a buffer in memory:
    ‘yy_scan_string’, ‘‘yy_scan_bytes’, and yy_scan_buffer

  57. Hi, The program requires to read the from the file that I pass during the execution but some how after I pass the file name it does nothing. Could help me out. The command prompt works fine but through GUI it is the problem.


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