Please comment this code.

stackADT.c

#include #include #include "sqjuggler.h"

struct node{ Item data; struct node *next; };

struct stack_type{ struct node *top; };

static void terminate(const char *message) { printf("%s ",message); exit(EXIT_FAILURE); }

stack create(int size) { Stack s=malloc(sizeof(struct stack_type)); if(s==NULL) terminate("Error in create: stack could not be created."); s->top==NULL; return s; }

void destroy(Stack s)

{ make_empty(s); free(s); }

void make_empty(Stack s) { while(!is_empty(s)) pop(s); }

bool is_empty(Stack s) { return s->top==NULL; }

bool is_full(Stack s) { return false; }

void push(Stack s, int i) { struct node *new_node=malloc(sizeof(struct node)); if(new_node==NULL) terminate("Error in push: stack is full.");

new_node->data=i; new_node->next=s->top; s->top=new_node; }

Item pop(Stack s) { struct node *old_top; Item i;

if(is_empty(s)) terminate("Error in pop: stack is empty.");

old_top=s->top; i=old_top->data; s->top=old_top->next; free(old_top); return i; }