#include"queue.h"

Queue::Queue()
{
	count=0;
	rear=maxqueue-1;
	front=0;
}

bool Queue::empty() const
{
	return count==0;
}

Error_code Queue::append(const Queue_entry &item)
{
	if(count>=maxqueue)return overflow;
	count++;
	rear=((rear+1)==maxqueue)?0:(rear+1);
	entry[rear]=item;
	return success;
}

Error_code Queue::serve()
{
	if(count<=0)return underflow;
	count--;
	front=((front+1)==maxqueue)?0:(front+1);
	return success;
}

Error_code Queue::retrieve(Queue_entry &item) const
{
	if(count<=0)return underflow;
	item=entry[front];
	return success;
}
bool Extended_queue::full() const{
	return count==maxqueue;
}
int Extended_queue::size()const{
	return count;
}
void Extended_queue::clear(){
	count=0;
	rear=front;
}
Error_code Extended_queue::serve_and_retrieve(Queue_entry &item){
	if(count==0)return underflow;
	count--;
	item=entry[front];
	front=((front+1)==maxqueue)?0:(front+1);
	return success;
}

comparequeue.cpp

#include "queue.h"
#include <iostream>
#include <string>
using namespace std;

void Introduction();
void Compare();

int main(){
	Introduction();
	Compare();
	return 0;
}
//show the introduction of the program
void Introduction(){
	cout<<"Hi! This program is compare two parts of characters."<<endl
		<<"First you should type in a line of characters which is supposed to consist of two parts "
		<<"separated by a colon ':' ."<<endl
		<<"And then enter <Enter> to quit put in"<<endl
		<<"Then I will show you a single character as follows :"<<endl
		<<"[N]  No colon on the line"<<endl
		<<"[L]  The left part (before the colon) is longer than the right"<<endl
		<<"[R]  The right part (after the colon) is longer than the left"<<endl
		<<"[D]  The left and the right parts have the same length but different"<<endl
		<<"[S]  The left and the right parts are exactly the same"<<endl
		<<"And enter [Ctrl+'Z'] to stop input"<<endl
		<<"So,just try it!"<<endl;
	return;
}

void Compare(){
	Extended_queue left_queue;
	char left_char;
	bool waiting=true;
	while(cin>>left_char && waiting){
		if(left_char==':'){
			waiting=false;  //if ':' is entered,quit the left input
			break;
		}
		else if(left_queue.full())
			cout<<"Queue is full!"<<endl; //Warning for the queue full
		else 
			left_queue.append(left_char);
		        //if the input is not ':' and there is space in the queue
		        //append the charcter to the queue
	}
	char right_char;
	bool same=true;
	while(!waiting && cin>>right_char){  //if ':' is input before 
		                                 //now input the righter charachters
		if(left_queue.empty()){
			cout<<"R"<<endl;    //if the left characters are all taken out
			                    //and the user is still inputing,right must longer than left
			                    //print [R]
			return;
		}
		else{
			left_queue.serve_and_retrieve(left_char);
			if(left_char!=right_char)
				same=false;    //if the character input now is different from
			                  //the one put into left before,set the bool same to 'false'
		}
	}
	if(waiting){
		cout<<"N"<<endl;   //if the user stop inputing while there is no ':' has been input
		                   //print [N]
		return ;
	}
	if(!left_queue.empty()){
		cout<<"L"<<endl;   //if user stop inputing while characters in left_queue are not all taken out
		                   //left must longer than right
		                   //print [L]
		return ;
	}
	if(left_queue.empty() && same){
		cout<<"S"<<endl;   //if user stop inputing while left_quque is just empty and bool same is true
		                   //left and right have the exactly same characters
		                   //print [S]
		return;
	}

	return;

}

实验截图：

1.实验中我以课本后面的练习题为例，实现并验证了顺序队列的更种功能。
2.队列与栈一样是在类中以数组存储数据，但由于队列先进先出的特点在实现存储形式上与栈有一定的不同。因为如果与栈一样对数据操作，队列会无限向后扩大，而前面取出过数据的地方将不会再被利用，十分浪费，也很容易溢出。所以我们采用循环数组来存储，这样合理利用了资源。但在类的实现要要极为时刻考虑周全rear和front的各种可能，要判断是不是循环到了前面，count在此时的功能也极为突出。
3.书中的程序看似简单，但实际判断各种输出情况的时候却极难考虑周全。我首先做出了简易的流程图，然后才写函数，具体分析及思路可见我源码的注释。另外本题还有另外一种实现思路：即将左右输入分别存放在两个队列中，边取去边比较，那样在逻辑上容易理解一些。但鉴于题目的要求，我还是用边从左边队列中取出边比较右边输入的方法。
4.我在实验中遇到的问题：
（1）自己一开始在循环判断用的是cin.get()=='\n'即遇到回车就停止输入，但却无法如料想中结束循环……最终采用cin>>a && waiting（用以标志‘：’的输入）来作为循环终止的条件，这样虽然可以运行，但用户必须输入Ctrl+‘Z’以结束输入。看来自己对输入流的理解与掌握还没有到位。
（2）另外在检验的时候，我发现输入‘：’之前是否输入回车情况是有区别的。如
输入“sam:sam”(无空格)，结果为“R”
输入“sam : sam”(有空格)，结构为“S”
显然后者是我希望得到的结果，我分析可能是前面情况‘：’被列入了right的判断，从而使结构右边比左边长。还没有想到如何改进。