postfixvalue.c

#include<stdio.h>
#include<conio.h>
int stack[20];
int top=-1;
void push(int x)
{
 stack[++top] = x;
}
int pop()
{
 return stack[top--];
}
void main()
{
 char exp[20];
 char *e;
 int n1,n2,n3,num;
 printf("Enter the expression:");
 scanf("%s",exp);
 e = exp;
 while(*e != '\0')
 {
  if(isdigit(*e))
  {
   num = *e - 48;
   push(num);
  }
  else
  {
   n1 = pop();
   n2 = pop();
   switch(*e)
   {
    case '+':n3 = n1 + n2;break;
    case '-':n3 = n2 - n1;break;
    case '*':n3 = n1 * n2;break;
    case '/':n3 = n2 / n1;break;
   }
   push(n3);
  }
  e++;
 }
 printf("\nThe result of expression %s  =  %d\n\n",exp,pop());
 getch();
}