practical 10 (B6)

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#include<stdio.h> //including header files
#include<stdlib.h>
#include<string.h>
char ip_sym[15],stack[15]; //declaring global variables
int ip_ptr=0,st_ptr=0,len,i;
char temp[2],temp2[2];
char act[15];
void check(); //declaring function
void main() //defining main
{
    printf("\n\t\t SHIFT REDUCE PARSER\n");
    printf("\n GRAMMER\n"); //defining grammar
    printf("\n E->E+E\n E->E/E");
    printf("\n E->E*E\n E->a/b");
    printf("\n Enter the input symbol:\t");
    gets(ip_sym); //take input string
    printf("\n\t Stack implementation table");
    printf("\n Stack\t\t Input symbol\t\t Action");
    //construct parse table
    printf("\n______\t\t ____________\t\t ______\n");
    printf("\n $\t\t%s$\t\t\t--",ip_sym);
    strcpy(act,"shift ");
    temp[0]=ip_sym[ip_ptr];
    temp[1]='\0';
    strcat(act,temp);
    len=strlen(ip_sym);
    for(i=0;i<=len-1;i++) //using for loop
    {
        stack[st_ptr]=ip_sym[ip_ptr]; //inserting in stack
        stack[st_ptr+1]='\0';
        ip_sym[ip_ptr]=' ';
        ip_ptr++;
        printf("\n $%s\t\t%s$\t\t\t%s",stack,ip_sym,act);
        strcpy(act,"shift ");
        temp[0]=ip_sym[ip_ptr];
        temp[1]='\0';
        strcat(act,temp);
        check(); //checking with grammar
        st_ptr++;
    }
    st_ptr++;
    check();
}
void check() //function definition
{
    int flag=0;
    temp2[0]=stack[st_ptr];
    temp2[1]='\0';
    if((!strcmp(temp2,"a"))||(!strcmp(temp2,"b")))
    {
        stack[st_ptr]='E';
        if(!strcmp(temp2,"a")) //checking for third production
            printf("\n $%s\t\t%s$\t\t\tE->a",stack, ip_sym);
        else
            printf("\n $%s\t\t%s$\t\t\tE->b\n",stack,ip_sym);
        flag=1;
    }
    if((!strcmp(temp2,"+"))||(strcmp(temp2,"*"))||(!strcmp(temp2,"/")))
    {
        flag=1;
    }
    if((!strcmp(stack,"E+E"))||(!strcmp(stack,"E\E"))||(!strcmp(stack,"E*E")))
    {
        strcpy(stack,"E");
        st_ptr=0;
        if(!strcmp(stack,"E+E")) //using if condition
            printf("\n $%s\t\t%s$\t\t\tE->E+E",stack,ip_sym);
        else if(!strcmp(stack,"E\E"))
            printf("\n $%s\t\t %s$\t\t\tE->E\E",stack,ip_sym);
        else
            printf("\n $%s\t\t%s$\t\t\tE->E*E",stack,ip_sym);
        flag=1;
    }
    if(!strcmp(stack,"E")&&ip_ptr==len)
    {
        printf("\n $%s\t\t%s$\t\t\tACCEPT\n",stack,ip_sym);
        exit(0);
    }
    if(flag==0)
    {
        printf("\n%s\t\t\t%s\t\t reject\n",stack,ip_sym);
        exit(0);
    }
    return;
} 

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