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Program of Deterministic Finite Automation (DFA) for identifier, real number with optional Integer and Fractional Part

Posted By: Easy Tutor     Category: C++ Programming     Views: 5847

Based on Deterministic Finite Automation (DFA) for a REAL number with optional Integer and Fractional Part.

-> find for the given string entered is whether
i> Identifier
ii> Integer number
iii> Real number
it check all posibility and determine the validity of entered string.

DFA for Real number
-> L = Letter
-> D = Digit
-> . = Decimal Point


================================================
||--------||--------NEXT SYMBOL---------------||
|| STATE =======================================
||--------||---L-----||-----D-----||----.-----||
||============================================||
||-START--||--ID-----||---INT-----||----S1----||
||-ID-----||--ID-----||---ID------||--INVALID-||
||-INT----||-INVALID-||---INT-----||--REAL----||
||-REAL---||-INVALID-||---REAL----||--INVALID-||
||-S1-----||-INVALID-||---REAL----||--INVALID-||
================================================

Code for Program of Deterministic Finite Automation (DFA) for identifier, real number with optional Integer and Fractional Part in C++ Programming


#include <iostream.h>
#include <conio.h>
#include <string.h>
#include <ctype.h>
#include <process.h>

void main()
{
    char inputstr[50];
    char nextSymbol,state[10]="START";
    int i;
    clrscr();

    cout<<"\n*****Scanner (Lexical Analysis) *****\n";
    cout<<"Enter String : ";
    cin.getline(inputstr,50,'\n');

    for(i=0;inputstr[i]!=NULL;i++)
    {
        nextSymbol = inputstr[i];

        if(strcmp(state,"INVALID")==0)
            break;

        //initially state of inputstr is in start.if(strcmp(state,"START")==0){
            if(isdigit(nextSymbol))
                strcpy(state,"INT");
            elseif(isalpha(nextSymbol))
                strcpy(state,"ID");
            elseif(nextSymbol=='.')
                strcpy(state,"S1");
            else
                strcpy(state,"INVALID");
        }
        elseif(strcmp(state,"ID")==0){
            if(isdigit(nextSymbol))
                strcpy(state,"ID");
            elseif(isalpha(nextSymbol))
                strcpy(state,"ID");
            else
                strcpy(state,"INVALID");
        }
        elseif(strcmp(state,"INT")==0){
            if(isdigit(nextSymbol))
                strcpy(state,"INT");
            elseif(nextSymbol=='.')
                strcpy(state,"REAL");
            else
                strcpy(state,"INVALID");
        }
        elseif(strcmp(state,"REAL")==0){
            if(isdigit(nextSymbol))
                strcpy(state,"REAL");
            else
                strcpy(state,"INVALID");
        }
        elseif(strcmp(state,"S1")==0){
            if(isdigit(nextSymbol))
                strcpy(state,"REAL");
            else
                strcpy(state,"INVALID");
        }
    }

    if(strcmp(state,"S1")==0 || strcmp(state,"INVALID")==0)
        cout<<"\n\nINVALID INPUT";
    else
        cout<<"\n\nString State is : "<<state;

end:
    getch();
}[/Code]
  
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Easy Tutor
Easy Tutor author of Program of Deterministic Finite Automation (DFA) for identifier, real number with optional Integer and Fractional Part is from United States. Easy Tutor says

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