pex5_1.cpp

数据结构C++代码,经典代码,受益多多,希望大家多多支持

#include <iostream.h>
#include <stdlib.h>
#include <fstream.h>

typedef double DataType;

// maximum size of a queue list
const int MaxQSize = 50;

class Queue
{
    private:
        // queue array and its parameters
        int front, rear, count;
        DataType qlist[MaxQSize];

    public:
        // constructor
        Queue (void);       // initialize integer data members
        
        // queue modification operations
        void QInsert(const DataType& item);
        DataType QDelete(void);
        void ClearQueue(void);
        
        // queue access
        DataType QFront(void) const;
        
        // queue test methods
        int QLength(void) const;
        int QEmpty(void) const;
        int QFull(void) const;
        
        void QPrint(void);
};
                                  
// initialize queue front, rear, count
Queue::Queue (void) : front(0), rear(0), count(0)
{}

// insert item into the queue 
void Queue::QInsert (const DataType& item)
{
    // terminate if queue is full
    if (count == MaxQSize)
    {
        cerr << "Queue overflow!" << endl;
        exit(1);
    }
    // increment count, assign item to qlist and update rear
    count++;
    qlist[rear] = item;
    rear = (rear+1) % MaxQSize;
}

// delete element from front of queue and return its value
DataType Queue::QDelete(void)
{
    DataType temp;

    // if qlist is empty, terminate the program
    if (count == 0)
    {
        cerr << "Deleting from an empty queue!" << endl;
        exit(1);
    }
    
    // record value at the front of the queue
    temp = qlist[front];

    // decrement count, advance front and return former front
    count--;
    front = (front+1) % MaxQSize;
    return temp;
}

// return value of the first entry 
DataType Queue::QFront(void) const
{
    return qlist[front];
}
  
// return number of queue elements
int Queue::QLength(void) const
{
    return count;
}

// test for an empty queue
int Queue::QEmpty(void) const
{
    // return the logical value count == 0
    return count == 0;
}

// test for a full queue
int Queue::QFull(void) const
{
    // return the logical value count == MaxQSize
    return count == MaxQSize;
}

// clear the queue by resetting count, front and rear to 0
void Queue::ClearQueue(void) 
{
    count = 0;
    front = 0; 
    rear = 0; 
}

void Queue::QPrint()
{
	// index moves circularly through the queue
	int index = front;
	int i = 1; 
	
	// print each of the count elements in the queue
	while (i <= count)
	{
		cout << qlist[index] << "  ";
		// every 8th element, generat a new line
		if (i % 8 == 0)
			cout << endl;
		// move to next queue element
		index = (index + 1) % MaxQSize;
		i++;
	}
}

void main(void)
{
	ifstream fin;
	double item;
	Queue  Q;
	
	fin.open("pq.dat", ios::in | ios::nocreate);
	if (!fin)
	{
		cerr << "File 'pq.dat' cannot be opened." << endl;
		exit(1);
	}
	
	// read the 20 double values from 'pq.dat' and insert
	// each into Q
	for (int i = 0; i < 20; i++)
	{
		fin >> item;
		Q.QInsert(item);
	}
	cout << endl;
	
	// test the method QPrint
	Q.QPrint();
}

/*
<Run>

<file 'pq.dat'>
1  2  3  4  5  6  7  8  10 
20  30 40  50  60  70  80
1.5  2.5  3.5 4.5

1  2  3  4  5  6  7  8
10  20  30  40  50  60  70  80
1.5  2.5  3.5  4.5  
*/