BCSL305 Program 5 A

#include<stdio.h>

#include<stdlib.h>

#include<math.h>

int i, top = -1;
int op1, op2, res, s[20];
char postfix[90], symb;

void push(int item)
{
    top = top + 1;
    s[top] = item;
}

int pop()
{
    int item;
    item = s[top];
    top = top - 1;
    return item;
}

void main()
{
    printf("\nEnter a valid postfix expression:\n");
    scanf("%s", postfix);
    for (i = 0; postfix[i] != '\0'; i++)
    {
        symb = postfix[i];
        if (isdigit(symb))
        {
            push(symb - '0');
        }
        else
        {
            op2 = pop();
            op1 = pop();
            switch (symb)
            {
            case '+':
                push(op1 + op2);
                break;
            case '-':
                push(op1 - op2);
                break;
            case '*':
                push(op1 * op2);
                break;
            case '/':
                push(op1 / op2);
                break;
            case '%':
                push(op1 % op2);
                break;
            case '$':
            case '^':
                push(pow(op1, op2));
                break;
            default:
                push(0);
            }
        }
    }
    res = pop();
    printf("\n Result = %d", res);
}