First Parser

Program : First Parser

#include<stdio.h>

#include<conio.h>

#include<stdlib.h>

#include<string.h>



void main() //main function

{

char gramar[10][10];

int ch=1,n=0;

char temp[10];

char first[23];

int m;

int j=0,i=0,k=3,flag=0;

char small[30]={'a','b','c','d','e','f','g','h',

'i','j','k','l','m','n','o','p',

'q','r','s','t','u','v','w','x',

'y','z','*','+','/','-','(',')'}; //check terminals



int p,h=1;

char sa[10];

char pa[10];

char temp1[10];

clrscr();

do

{

printf("\nenter grammar");

scanf("%s",gramar[n]); //get the grammar

printf("\ncontinue( 0 or 1 )");

scanf("\n%d",&ch);

n++;

}

while(ch==1);

printf("\n\nTHE ENTERED GRAMMAR IS");

for(i=0;i<n;i++)

printf("\n%s",gramar[i]);

do

{

printf("\nenter the grammar symbol whose first has to be found");

scanf("%s",sa); //accept symbol

label:

for(i=0;i<n;i++)

{

strcpy(temp,gramar[i]);

if(sa[0]==temp[0])

{

strcpy(temp1,temp); //copy to temp1

break;

}

}

k=2;

j=0;

for(i=0;i<35;i++) //check if terminal

{

if(temp1[2]==small[i])

{

flag=1;

first[j]=temp1[k];

}

}

j++;

while(k<strlen(temp1))

{

if(temp1[k]=='|')

{

for(i=0;i<35;i++) //check if terminal

{

if(temp1[k+1]==small[i])

{

flag=1;

first[j]=temp1[k+1];

}

}

j++;

goto l1;

}

k++;

}

l1:

if(flag==0) //if no terminal is found

{

sa[0]=temp1[2];

goto label;

}

first[j]='\0';

printf("\n { ");

for(i=0;i<strlen(first);i++) //print the first of symbol

{

if(i+1==strlen(first))

printf("%c",first[i]);

else

printf("%c , ",first[i]);

}

printf(" } ");

printf("\n do u want to continue ?? yes(1) or no(0) ");

scanf("\n%d",&h);

}

while(h!=0);

getch();

}