implement stack using link list in c

1#include <stdio.h>
2#include <stdlib.h>
3#define TRUE 1
4#define FALSE 0
5
6struct node
7{
8    int data;
9    struct node *next;
10};
11typedef struct node node;
12
13node *top;
14
15void initialize()
16{
17    top = NULL;
18}
19
20void push(int value)
21{
22    node *tmp;
23    tmp = malloc(sizeof(node));
24    tmp -> data = value;
25    tmp -> next = top;
26    top = tmp;
27}
28
29int pop()
30{
31    node *tmp;
32    int n;
33    tmp = top;
34    n = tmp->data;
35    top = top->next;
36    free(tmp);
37    return n;
38}
39
40int Top()
41{
42    return top->data;
43}
44
45int isempty()
46{
47    return top==NULL;
48}
49
50void display(node *head)
51{
52    if(head == NULL)
53    {
54        printf("NULL\n");
55    }
56    else
57    {
58        printf("%d\n", head -> data);
59        display(head->next);
60    }
61}
62
63int main()
64{
65    initialize();
66    push(10);
67    push(20);
68    push(30);
69    printf("The top is %d\n",Top());
70    pop();
71    printf("The top after pop is %d\n",Top());
72    display(top);
73    return 0;
74}
75