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
|
/***********************************************************************
* Code listing from "Advanced Linux Programming," by CodeSourcery LLC *
* Copyright (C) 2001 by New Riders Publishing *
* See COPYRIGHT for license information. *
***********************************************************************/
/* Provide a stack of "number"s. */
#include <assert.h>
#include <stdlib.h>
#include "definitions.h"
/* Create an empty stack. */
Stack create_stack ()
{
return 0;
}
/* Return nonzero if the stack is empty. */
int empty_stack (Stack stack)
{
return stack == 0;
}
/* Remove the number at the top of a non-empty stack. If the stack is
empty, abort. */
number pop_stack (Stack* stack)
{
number answer;
Stack rest_of_stack;
assert (!empty_stack (*stack));
answer = (*stack)->element_;
rest_of_stack = (*stack)->next_;
free (*stack);
*stack = rest_of_stack;
return answer;
}
/* Add a number to the beginning of a stack. */
void push_stack (Stack* stack, number n)
{
Stack new_stack = malloc (sizeof (struct StackElement));
new_stack->element_ = n;
new_stack->next_ = *stack;
*stack = new_stack;
}
/* Remove all the stack's elements. */
void clear_stack (Stack* stack)
{
while (!empty_stack (*stack)) {
number top = pop_stack (stack);
destroy_number (top);
}
}
|
