stack.cpp

Think in C++文中代码实现

// File referred to (not printed) on page 141 in "Thinking in C++" by Bruce Eckel
//////////////////////////////////////////////////
// From the compressed package ECKELT02.ZIP 4/11/95
// (Original ECKELT01.ZIP dated 2/21/95)
// Copyright (c) Bruce Eckel, 1995 
// Source code file from the book "Thinking in C++", 
// Prentice Hall, 1995, ISBN: 0-13-917709-4
// All rights reserved EXCEPT as allowed by the following 
// statements: You may freely use this file for your own 
// work, including modifications and distribution in 
// executable form only. You may copy and distribute this 
// file, as long as it is only distributed in the complete 
// (compressed) package with the other files from this 
// book and you do not remove this copyright and notice. 
// You may not distribute modified versions of the source 
// code in this package. This package may be freely placed 
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// product vendor disks. You may not use this file in 
// printed media without the express permission of the 
// author. Bruce Eckel makes no 
// representation about the suitability of this software 
// for any purpose. It is provided "as is" without express 
// or implied warranty of any kind. The entire risk as to 
// the quality and performance of the software is with 
// you. Should the software prove defective, you assume 
// the cost of all necessary servicing, repair, or 
// correction. 
// If you think you've found an error, please 
// email all modified files with loudly commented changes 
// to: [e-mail] (please use the same 
// address for non-code errors found in the book).
//////////////////////////////////////////////////

//: STACK.CPP -- Nested linked list definitions
#include <stdlib.h>
#include <assert.h>
#include "..\2\stack.h"

void stack::link::initialize(
    void* Data, link* Next) {
  data = Data;
  next = Next;
}

void stack::initialize() { head = 0; }

void stack::push(void* Data) {
  link* newlink = (link*)malloc(sizeof(link));
  assert(newlink);
  newlink->initialize(Data, head);
  head = newlink;
}

void* stack::peek() { return head->data; }

void* stack::pop() {
  if(head == 0) return 0;
  void* result = head->data;
  link* oldHead = head;
  head = head->next;
  free(oldHead);
  return result;
}

void stack::cleanup() {
  link* cursor = head;
  while(head) {
    cursor = cursor->next;
    free(head->data);  // Assumes a malloc!
    free(head);
    head = cursor;
  }
}