stack

#include <stdlib.h>
#include <stdio.h>

typedef struct node {
    int value;
    struct node *next;
} Node;

int size(const Node *head);
void print_stack(const Node* head);
int top(const Node* head);
int pop(Node **head);
void push(Node **head, int value);

void main() {
    /*
    int i;
    Node *head = NULL;
    for (i = 0; i < 10; i++) {
        push(&head, i);
    }
    printf("size = %d\n", size(head));
    while (head) {
        printf("%d ", top(head));
        printf("%d ", pop(&head));
    }
    */
    return 0;
}

void push(Node **head, int value){
    Node *temp = malloc(sizeof(Node));
    temp -> next = *head;
    temp -> value = value;
    *head = temp;
}

int pop(Node **head){
    Node *out;
    int value;
    if ( *head == NULL ) return 0;
    out = *head;
    *head = (*head) -> next;
    value = out -> value;
    free(out);
    return value;
}

int top(const Node* head) {
    if ( head == NULL ) return 0;
    return head->value;
}

void print_stack(const Node* head) {
    printf("stack > ");
    while (head) {
        printf("%d ", head->value);
        head = head->value;
    }
    printf("\n");
}

int size(const Node *head) {
    int size = 0;
    while (head) {
        size++;
        head = head->next;
    }
    return size;
}