SLR

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
char ip_sym[15],stack[15];
int ip_ptr=0,st_ptr=0,len,i;
char temp[2];
char act[15];
void check();

void main()
 {
  printf("\n\t\t SHIFT REDUCE PARSER\n");
  printf("\n GRAMMER\n");
  printf("\n E->E+T|T\n T->T* F | F");
  printf("\n F-> (E) | id \n ");
  printf("\n Enter the input symbol:\t");
  scanf("%s",ip_sym);
  printf("\n\t Stack implementation table\n");
  printf("\n Stack\t\t\tInput symbol\t\t\t Action");
  printf("\n______\t\t\t ____________\t\t \t______\n");
  printf("\n $\t\t\t%s$\t\t\t--",ip_sym); /*first step empty action */
  strcpy(act,"Shift ");
  if (ip_sym[ip_ptr]=='(')
  {
   temp[0]=ip_sym[ip_ptr];
   temp[1]='\0';
  }
  else
  {
   temp[0]=ip_sym[ip_ptr];
   temp[1]=ip_sym[ip_ptr+1];
   temp[2]='\0';
  }

  strcat(act,temp);
  len=strlen(ip_sym);
  
 for(i=0;i<=len-1;i++)
  {
   if(ip_sym[ip_ptr]=='i' &&ip_sym[ip_ptr+1]=='d')
   {
    stack[st_ptr]=ip_sym[ip_ptr];
    st_ptr++;
    ip_sym[ip_ptr]=' ';
    ip_ptr++;
    stack[st_ptr]= ip_sym[ip_ptr];
    stack[st_ptr+1]='\0';
    ip_sym[ip_ptr]=' ';
    ip_ptr++;
   }
  else
  {
   stack[st_ptr]=ip_sym[ip_ptr];
   stack[st_ptr+1]='\0';
   ip_sym[ip_ptr]=' ';
   ip_ptr++;
  }
  
  printf("\n $%s\t\t\t%s$\t\t\t%s",stack,ip_sym,act); /* second print with action shift*/
  strcpy(act,"shift ");
  if (ip_sym[ip_ptr]=='(' || ip_sym[ip_ptr]=='*' || ip_sym[ip_ptr]=='+' || ip_sym[ip_ptr]==')')
  {
   temp[0]=ip_sym[ip_ptr];
   temp[1]='\0';
  }
  else
  {
   temp[0]=ip_sym[ip_ptr];
   temp[1]=ip_sym[ip_ptr+1];
   temp[2]='\0';
  }
  strcat(act,temp);
  check();
  st_ptr++;
 }
 
  st_ptr++;
  check();
}


void check()
{
  int flag=0;
  while(1)
  {
   if (stack[st_ptr]=='d'&& stack[st_ptr-1]=='i')
   {
    stack[st_ptr-1]='F';
    stack[st_ptr]='\0';
    st_ptr--;
    flag=1;
    printf("\n $%s\t\t\t%s$\t\t\tF->id",stack, ip_sym);
   }
  
   if (stack[st_ptr]==')' && stack[st_ptr-1]=='E' && stack[st_ptr-2]=='(')
   {
    stack[st_ptr-2]='F';
    stack[st_ptr-1]='\0';
    flag=1;
    st_ptr=st_ptr-2;
    printf("\n $%s\t\t\t%s$\t\t\tF->id",stack, ip_sym);
   }
   
   if (stack[st_ptr]=='F' && stack[st_ptr-1]=='*' && stack[st_ptr-2]=='T')
   {
     // stack[st_ptr-2]='T';
     stack[st_ptr-1]='\0';
     st_ptr= st_ptr-2;
     flag=1;
     printf("\n $%s\t\t\t%s$\t\t\tT->T*F",stack, ip_sym);
   }
 
   else
   {
     if (stack[st_ptr]=='F')
     {
       stack[st_ptr]='T';
       flag=1;
       printf("\n $%s\t\t\t%s$\t\t\tT->F",stack, ip_sym);
     }
   }
     
     if( stack[st_ptr]=='T' && stack[st_ptr-1]=='+' && stack[st_ptr-2]=='E' && ip_sym[ip_ptr]!='*' )
     {
      //stack[st_ptr-2]='E';
      stack[st_ptr-1]='\0';
      st_ptr= st_ptr-2;
      flag=1;
      printf("\n $%s\t\t\t%s$\t\t\tE->E+T",stack, ip_sym);
     }
     
     else if ((stack[st_ptr]=='T' && ip_sym[ip_ptr]== '+') || (stack[0]=='T' && ip_sym[ip_ptr]== '\0') ||
             (stack[st_ptr]=='T' && ip_sym[ip_ptr]== ')'))
     {
       stack[st_ptr]='E';
       flag=1;
       printf("\n $%s\t\t\t%s$\t\t\tE->T",stack, ip_sym);
     } 
    
     if((stack[st_ptr]=='T' && ip_sym[ip_ptr]== '*') ||
        (stack[st_ptr]=='E' && ip_sym[ip_ptr]==')')||
        (stack[st_ptr]=='E' && ip_sym[ip_ptr]=='+')||
        (stack[st_ptr]=='+'&& ip_sym[ip_ptr]=='i' && ip_sym[ip_ptr+1]=='d')||
        (stack[st_ptr]== '(' && ip_sym[ip_ptr]=='i' && ip_sym[ip_ptr+1]=='d') ||
        (stack[st_ptr]== '(' && ip_sym[ip_ptr]=='(')||
        (stack[st_ptr]=='*'&& ip_sym[ip_ptr]=='i' && ip_sym[ip_ptr+1]=='d' ) ||
        (stack[st_ptr]=='*'&& ip_sym[ip_ptr]=='(') ||
        (stack[st_ptr]=='+'&& ip_sym[ip_ptr]=='('))
     {
        flag=2;
     }
    
     if(!strcmp(stack,"E")&& ip_sym[ip_ptr]=='\0')
     {
       printf("\n $%s\t\t\t%s$\t\t\tACCEPT\n",stack,ip_sym);

       exit(0);
     }
 
    if(flag==0)
    {
      printf("\n%s\t\t\t%s\t\t\treject\n",stack,ip_sym);
      exit(0);
    }
   
   if (flag==2) 
    return;
   flag=0;
 }
}