Logo 
Search:

C++ Programming Articles

Submit Article
Home » Articles » C++ Programming » Mathematics ProgramRSS Feeds

Program to implement Lexical Analyzer

Posted By: Easy Tutor     Category: C++ Programming     Views: 19400

A C++ Program to implement Lexical Analyzer.

Code for Program to implement Lexical Analyzer in C++ Programming



 # include <iostream.h>
 # include <fstream.h>
 # include <string.h>
 # include <stdlib.h>
 # include <stdio.h>
 # include <conio.h>
 # include <ctype.h>

 /*************************************************************************///--------------------------  Global Variables  -------------------------///*************************************************************************/constint iRows = 34;
 constint iCols = 15;

 int iTT[iRows][iCols] = {0};

 /*************************************************************************///------------------------  Function Definitions  -----------------------///*************************************************************************///------------------------  loadTransitionTable( )  ---------------------//void loadTransitionTable( )
 {
    fstream File("tt.txt", ios::in|ios::nocreate);

    if (!File)
    {
       cout << "\n Unable to open the input file." << endl;
       cout << "\n Press any key to exit.";

       getch( );
       exit(0);
    }

    char sInput[100]={NULL};

    for (int i = 0; i < iRows; i ++)
    {
       strset(sInput, NULL);

       File.getline(sInput, 80);

       char *sPtr=NULL;

       sPtr = strtok(sInput, " ");

       iTT[i][0] = atoi(sPtr);

       for(int j = 1; j < iCols; j ++)
       {
      sPtr=strtok(NULL, " ");

      iTT[i][j] = atoi(sPtr);
       }
    }

    File.close( );
 }

 //---------------------------  getNextState( )  -------------------------//int getNextState(int iState, char cChar)
 {
    if (isalpha(cChar))
       return iTT[iState][1];

    elseif (isdigit(cChar))
       return iTT[iState][2];

    elseif (cChar == '.')
       return iTT[iState][3];

    elseif (cChar == '"')
       return iTT[iState][4];

    elseif (cChar == '_')
       return iTT[iState][6];

    elseif (cChar == '+')
       return iTT[iState][7];

    elseif (cChar == '=')
       return iTT[iState][8];

    elseif (cChar == '-')
       return iTT[iState][9];

    elseif (cChar == '%')
       return iTT[iState][10];

    elseif (cChar == '!')
       return iTT[iState][11];

    elseif (cChar == '>')
       return iTT[iState][12];

    elseif (cChar == '<')
       return iTT[iState][13];

    elseif (cChar == '/')
       return iTT[iState][14];

    return iTT[iState][0];
 }

 //----------------------------  isKeyword( )  ----------------------------//int isKeyword(char* sToken)
 {
    if (strlen(sToken) > 16 || strlen(sToken) == 0)
       return 0;

    char sKeywords[64][20] = {
                   "asm","auto","bool","break","case","catch",
                   "char","class","const","const_cast",
                   "continue","default","delete","do","double",
                   "dynamic_cast","else","enum","explicit",
                   "export","extern","false","float","for",
                   "friend","goto","if","inline","int","long",
                   "main","mutable","namespace","new",
                   "operator","private","protected","public",
                   "register","reinterpret_cast","return",
                   "short","signed","sizeof","static",
                   "static_cast","struct","switch","template",
                   "this","throw","true","try","typedef",
                   "typeid","typename","union","unsigned","using",
                   "virtual","void","volatile","wchar_t","while"
                 };

    for(int iCount = 0; iCount < 64; iCount ++)
    {
       if (strcmpi(sKeywords[iCount], sToken) == 0)
      return 1;
    }

    return 0;
 }

 /*************************************************************************///-------------------------------  main( )  -----------------------------///*************************************************************************/int main( )
 {
    clrscr( );

    loadTransitionTable( );

    fstream File("input.txt", ios::in|ios::nocreate);

    if (!File)
    {
       cout<<"\n Unable to open the input file."<<endl;
       cout<<"\n Press any key to exit.";

       getch( );
       exit(0);
    }

    char sToken[255] = {NULL};
    int iTokenIndex = 0;

    char cChar = NULL;
    int iState = 0;
    int iFlag = 0;

    char cTemp = File.get( );

    do
    {
       Start:

       if (iFlag == 0)
       {
      cChar = cTemp;
      cTemp = File.get( );
       }

       else
      iFlag = 0;

       if (cChar == '/' && cTemp == '/')
       {
      while(File.get( ) != '\n')
      {
         if (File.eof( ))
        goto End;
      }

      cout<<'\r';

      cTemp = File.get( );

      goto Start;
       }

       if (cChar == '/' && cTemp == '*')
       {
      cTemp = File.get( );

      do
      {
         cChar = cTemp;
         cTemp = File.get( );

         if (File.eof( ))
        goto End;
      }
      while(cChar != '*' && cTemp != '/');

      cout<<'\r';

      cTemp = File.get( );

      goto Start;
       }

       iState = getNextState(iState, cChar);

       switch (iState)
       {
      case  0 :  cout << cChar;

             iState = 0;
             iTokenIndex = 0;

             strset(sToken, NULL);

             break;

      case  1 :
      case  3 :
      case  5 :
      case  7 :
      case 10 :
      case 14 :
      case 18 :
      case 25 :
      case 26 :  sToken[iTokenIndex] = cChar;
             iTokenIndex ++;

             break;

      case  2 :  if (isKeyword(sToken))
            cout << sToken;

             else
            cout << "<ID>";

             iState = 0;
             iTokenIndex = 0;
             iFlag = 1;

             strset(sToken, NULL);

             break;

      case  4 :  cout << "<INT>";

             iState = 0;
             iTokenIndex = 0;
             iFlag = 1;

             strset(sToken, NULL);

             break;

      case  6 :  cout << "<FLOAT>";

             iState = 0;
             iTokenIndex = 0;
             iFlag = 1;

             strset(sToken, NULL);

             break;

      case  8 :  cout << "<STR>";

             iState = 0;
             iTokenIndex = 0;

             strset(sToken, NULL);

             break;

      case  9 :
      case 11 :
      case 12 :
      case 13 :
      case 15 :
      case 16 :
      case 17 :
      case 19 :
      case 20 :
      case 21 :
      case 22 :
      case 23 :
      case 24 :
      case 27 :
      case 28 :  cout << "<OPR>";

             if (cChar != '+' && cChar != '-' && cChar != '/'
                && cChar != '>' && cChar != '<' && cChar != '=')
            iFlag = 1;

             iState = 0;
             iTokenIndex = 0;

             strset(sToken, NULL);

             break;

      case 30 :
      case 33 :  iState = 0;
             iTokenIndex = 0;

             strset(sToken, NULL);

             break;
       }
    }
    while(!File.eof( ));

    End:

    getch( );
    return 0;
 }

 /*************************************************************************///------------------------------  THE END  ------------------------------///*************************************************************************/
  
Share: 


Didn't find what you were looking for? Find more on Program to implement Lexical Analyzer Or get search suggestion and latest updates.

Easy Tutor
Easy Tutor author of Program to implement Lexical Analyzer is from United States. Easy Tutor says

Hello Friends,

I am Free Lance Tutor, who helped student in completing their homework.

I have 4 Years of hands on experience on helping student in completing their homework. I also guide them in doing their final year projects.

I have share many programs on this website for everyone to use freely, if you need further assistance, than please contact me on easytutor.2ya [at the rate] gmail [dot] com

I have special discount scheme for providing tutor services. I am providing tutor service to students from various contries, currently most of my students are from United States, India, Australia, Pakistan, Germany, UK and Canada.

I am also here to expand my technical network to receive more opportunity in my career, make friends to help them in resolving their technical problem, learn and share my knowledge, If you like to be my friend, Please send me friend request.

Thanks,
Happy Programming :)

 
View All Articles

 
Please enter your Comment

  • Comment should be atleast 30 Characters.
  • Please put code inside [Code] your code [/Code].

 
No Comment Found, Be the First to post comment!