SP Practical 5

Practical : 5

Subject : System Programming

Aim : C++ program to find FIRST of given grammer

Source Code :

#include<stdio.h>

#include<ctype.h>

void FIRST(char[],char );

void addToResultSet(char[],char);

int numOfProductions;

char productionSet[10][10];

main()

{

    int i;

    char choice;

    char c;

    char result[20];

    printf("How many number of productions ? :");

    scanf(" %d",&numOfProductions);

    for(i=0;i<numOfProductions;i++)

    {

            printf("Enter productions Number %d : ",i+1);

            scanf(" %s",productionSet[i]);

    }

    do

    {

            printf("\n Find the FIRST of  :");

            scanf(" %c",&c);

            FIRST(result,c);

            printf("\n FIRST(%c)= { ",c);

            for(i=0;result[i]!='\0';i++)

            printf(" %c ",result[i]);

            printf("}\n");

             printf("press 'y' to continue : ");

            scanf(" %c",&choice);

    }

    while(choice=='y'||choice =='Y');

}

void FIRST(char* Result,char c)

{

    int i,j,k;

    char subResult[20];

    int foundEpsilon;

    subResult[0]='\0';

    Result[0]='\0';

    if(!(isupper(c)))

    {

            addToResultSet(Result,c);

                   return ;

    }

    for(i=0;i<numOfProductions;i++)

    {

            if(productionSet[i][0]==c)

            {

 if(productionSet[i][2]=='$') addToResultSet(Result,'$');

      else

                {

                        j=2;

                        while(productionSet[i][j]!='\0')

                        {

                        foundEpsilon=0;

                        FIRST(subResult,productionSet[i][j]);

                        for(k=0;subResult[k]!='\0';k++)

                            addToResultSet(Result,subResult[k]);

                         for(k=0;subResult[k]!='\0';k++)

                             if(subResult[k]=='$')

                             {

                                     foundEpsilon=1;

                                     break;

                             }

                         if(!foundEpsilon)

                             break;

                         j++;

                        }

                }

    }

}

    return ;

}

void addToResultSet(char Result[],char val)

{

    int k;

    for(k=0 ;Result[k]!='\0';k++)

            if(Result[k]==val)

                return;

    Result[k]=val;

    Result[k+1]='\0';

}

Output :