SP Practical 7

Practical : 7

Subject : System Programming

Aim : Implement Recursive Descendent Parsing for the given Grammar.

• E -> T + E / T

• T -> F * T / F

• F -> ( E ) / i

Source Code :

#include<stdio.h>

#include<string.h>

#include<ctype.h>

char input[10];

int i,error;

void E();

void T();

void Eprime();

void Tprime();

void F();

void main()

{

            i=0;

            error=0;

            printf("Enter an arithmetic expression   :  ");

            gets(input);

            E();

            if(strlen(input)==i&&error==0)

                        printf("\nAccepted..!!!\n");

            else

                        printf("\nRejected..!!!\n");

}

void E()

{

     T();

     Eprime();

}

void Eprime()

{

     if(input[i]=='+')

     {

                 i++;

               T();

                Eprime();

     }

}

void T()

{

     F();

     Tprime();

}

void Tprime()

{

     if(input[i]=='*')

     {

               i++;

               F();

               Tprime();

     }}

void F()

{if(isalnum(input[i]))

                        i++;

            else if(input[i]=='(')

              { i++;

                          E();

                          if(input[i]==')')

                                    i++;

              else error=1;

              }

              else

                        error=1;

}

Output :