programs/poststack.c at main · AnjanaPrakash007/programs · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#include<ctype.h>
#include<string.h>
struct node
{
  int data;
  struct node *next;
};
struct node *top = NULL;

void push(int n)
{
  struct node *new;
  new = (struct node *)malloc(sizeof(struct node));
  new->data = n;
  new->next = top;
  top = new;
}

int pop()
{
  int data;
  struct node *temp;
  temp = top;
  data = temp->data;
  top = top->next;
  free(temp);
  return data;
}
int main()
{
  char postfix[100],e;
  int i=0,a,b,r;
  printf("Enter the postfix expression: ");
  fgets(postfix,100,stdin);
  for(i=0;i<strlen(postfix) - 1; i++)
  {
    e = postfix[i];
    if(isdigit(e))
    {
      push(e - '0');
    }
    else
    {
      a = pop();
      b = pop();
      switch(e)
      {
        case '+':
          r = a+b;
          break;
        case '-':
          r = b-a;
          break;
        case '*':
          r = a*b;
          break;
        case '/':
          r = b/a;
          break;
        case '^':
          r = pow(b,a);
          break;
      }
      push(r);
    }
  }
  printf("\nResult=%d\n\n",r);
}