c++primer plus清单12.10,12.11,12.12

首先
// stdafx.h : 标准系统包含文件的包含文件，
// 或是经常使用但不常更改的
// 特定于项目的包含文件
//

#ifndef QUEUE_H_
#define QUEUE_H_
class Customer
{
private:
long arrive;
int processtime;
public:
Customer() { arrive = processtime = 0; }
void set(long when);
long when() const { return arrive; }
int ptime()const { return processtime; }
};
typedef Customer Item;
class Queue
{
private:
struct Node
{
Item item;
struct Nodenext;
};
enum { Q_SIZE = 10 };
Nodefront;
Node*rear;
int items;
const int qsize;
Queue(const Queue&q) :qsize(0) {};
Queue&operator=(const Queue&q) { return *this; }
public:
Queue(int qs = Q_SIZE);
~Queue();
bool isempty()const;
bool isfull()const;
int queuecount()const;
bool enqueue(const Item&item);
bool dequeue(Item&item);
};
#endif
其次
#include “queue.h”
#include
Queue::Queue(int qs):qsize(qs)
{
front = rear = NULL;
items = 0;
}
Queue ::~Queue()
{
Node *temp;
while(front!=NULL)
{
temp = front;
front = front->next;
delete temp;

}

}

bool Queue::isempty() const
{
return items==0;
}

bool Queue::isfull() const
{
return items==qsize;
}

int Queue::queuecount() const
{
return items;
}

bool Queue::enqueue(const Item & item)
{if(isfull())
return false;
Node *add = new Node;
add->item = item;
add->next = NULL;
items++;
if (front == NULL)
front = add;
else rear->next = add;
rear = add;
return true;

}

bool Queue::dequeue(Item & item)
{if(front==NULL)
return false;
item = front->item;
items–;
Node*temp = front;
front = front->next;
delete temp;
if (items == 0)
rear = NULL;
return true;

}
void Customer::set(long when)
{
processtime = std::rand() % 3 + 1;
arrive = when;
}
最后
// queue.cpp: 定义控制台应用程序的入口点。
//

#include “queue.h”
#include
#include
#include
#include"queue.h"
const int MIN_PER_HR = 60;
bool newcustomer(double x);
int main()
{
using std::cin;
using std::cout;
using std::endl;
using std::ios_base;
std::srand(std::time(0));
cout << “Case study :Bank of Heather Automatic Teller\n”;
cout << “Enter maxium size of queue :”;
int qs;
cin >> qs;
Queue line(qs);
cout << “Enter the number of simulation hours :”;
int hours;
cin >> hours;
long cyclelimit = MIN_PER_HR*hours;
cout << “Enter the average number of customers per hour:”;
double perhour;
cin >> perhour;
double min_per_cust;
min_per_cust = MIN_PER_HR;
Item temp;
long turnaways = 0;
long customers = 0;
long served = 0;
long sum_line = 0;
int wait_time = 0;
long line_wait = 0;
for(int cycle=0;cycle<cyclelimit;cycle++)
{
if (newcustomer(min_per_cust))
{
if (line.isfull())
turnaways;
else
{
customers++;
temp.set(cycle);
line.enqueue(temp);
}
}
if(wait_time<=0&&!line.isempty())
{
line.dequeue(temp);
wait_time = temp.ptime();
line_wait += cycle - temp.when();
served++;
}
if (wait_time > 0)
wait_time–;
sum_line += line.queuecount();
}
if (customers > 0)
{
cout << “customers accepted : " << customers << endl;
cout << " customers served: " << served << endl;
cout << " turnaways :” << turnaways << endl;
cout << "average queue size : ";
cout.precision(2);
cout.setf(ios_base::fixed, ios_base::floatfield);
cout << (double)sum_line / cyclelimit << endl;
cout << "average wait time " << (double)line_wait / served << “minutes\n”;
}
else
cout << “No customers!\n”;
cout << “Done!\n”;
system(“pause”);
return 0;
}

bool newcustomer(double x)
{
return (std::rand())*x / RAND_MAX < 1;
}