shift reduce

shift reduce parser


#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],temp2[2];
char act[15];
void check();
void main()
{
    clrscr();
printf("\n\n\t Shift Reduce Parser\n");
printf("\n\t***** ****** ******");
printf("\n Grammar\n\n");
printf("E->E+E\nE->E/E\n");
printf("E->E*E\nE->a/b");
printf("\n Enter the Input Symbol:\t");
for(i=0;i<5;i++)
{
scanf("%c",&ip_sym[i]);
}
printf("\n\n\t Stack Implementation Table");
printf("\n Stack\t\t Input Symbol\t\t Action");

strcpy(act,"shift");
temp[0]=ip_sym[ip_ptr];
temp[1]='\0';
strcat(act,temp);
printf("\n $\t\t %s$\t\t\t%s ",ip_sym,act);
len=strlen(ip_sym);

for(i=0;i<=len-1;i++)
{
stack[st_ptr]=ip_sym[ip_ptr];
stack[st_ptr+1]='\0';
ip_sym[ip_ptr]=' ';
//printf("\n$%s\t\t%s$\t\t\t",stack,ip_sym);

ip_ptr++;

strcpy(act,"shift");
temp[0]=ip_sym[ip_ptr];
temp[1]='\0';
strcat(act,temp);

check();
st_ptr++;
}
st_ptr++;
check();
check();
}
void check()
{
int flag=0;
temp2[0]=stack[st_ptr];
temp2[1]='\0';
if(!strcmp(temp2,"a"))
{
printf("\n$%s\t\t%s$\t\t\tE->a",stack,ip_sym);
stack[st_ptr]='E';
if(ip_ptr!=len)
   printf("\n$%s\t\t%s$\t\t\t%s",stack,ip_sym,act);

flag=1;
}
 if(!strcmp(temp2,"b"))
{
printf("\n$%s\t\t%s$\t\t\tE->b",stack,ip_sym);
stack[st_ptr]='E';
if(ip_ptr!=len)
    printf("\n$%s\t\t%s$\t\t\t%s",stack,ip_sym,act);
flag=1;
}


if((!strcmp(temp2,"+"))||(!strcmp(temp2,"*"))||(!strcmp(temp2,"/")))
{
printf("\n$%s\t\t%s$\t\t\t%s",stack,ip_sym,act);
flag=1;
}
if((!strcmp(stack,"E+E"))||(!strcmp(stack,"E/E"))||(!strcmp(stack,"E*E")))
{
if(!strcmp(stack,"E+E"))
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);

strcpy(stack,"E");
st_ptr=0;
flag=1;

}
if(!strcmpi(stack,"E")&&ip_ptr==len)
{
printf("\n$%s\t\t%s$\t\t\tAccept",stack,ip_sym);
getch();
exit(0);
}
if(flag==0)
{
printf("\n$%s\t\t%s$\t\t\tReject",stack,ip_sym);
getch();
exit(0);
}
return;
}