POSTFIX Evaluation

POSTFIX Evaluation

#include<stdio.h>

#include<conio.h>

#include <ctype.h>

int s[20];

int top=-1;       

push(int elem)

{ 

 top++;                    


 s[top]=elem;

}

int pop()

{                      

 return(s[top--]);

}

void main()

{                         

 char pofx[50],ch;

 int i=0,op1,op2;

 printf("\n\nRead the Postfix Expression ? ");

 scanf("%s",pofx);

 while( (ch=pofx[i++]) != '\0')

 {

  if(isdigit(ch)) 
   push(ch-'0'); 

  else

  {        

   op2=pop();

   op1=pop();

   switch(ch)

   {

   case '+':
   push(op1+op2);
    break;

   case '-':
   push(op1-op2); 
   break;

   case '*':
   push(op1*op2);
   break;

   case '/':
   push(op1/op2); 
   break;

   }

  }

 }

 printf("\n Given Postfix Expn: %s\n",pofx);

 printf("\n Result after Evaluation: %d\n",s[top]);
getch();

}