2.Delimiter Matching

最新推荐文章于 2021-02-27 02:36:25 发布

原创最新推荐文章于 2021-02-27 02:36:25 发布 · 1.5k 阅读

3 ·

CC 4.0 BY-SA版权

文章标签：

#C++ #数据结构

Prerequisites, Goals, and Outcomes

Prerequisites: Students should have mastered the following prerequisite skills.

· Stack - Understanding of the implementation of stack.

· Templates - Creation and use of template classes

· File IO - Basic file IO skills

Goals: This assignment is designed to reinforce the student's understanding of the structure and use of stack as containers.

Outcomes: Students successfully completing this assignment would master the following outcomes.

· Familiarize how to implement a template class

· Familiarize the structure and the use of the stack

Background

Compilers check your programs for syntax errors, but frequently a lack of one symbol (such as a missing brace or comment starter) will cause the compiler to spill out a hundred lines of diagnostics without identifying the real error.

A useful tool in this situation is a program that checks whether everything is balanced. Thus, every right brace, bracket, and parenthesis must correspond to their left counterparts. The sequence [()] is legal, but [(]) is wrong. Obviously, it is not worthwhile writing a huge program for this, but it turns out that it is easy to check these things.

Description

Make an empty stack. Read characters until end of file. If the character is an open anything, push it onto the stack. If it is a close anything, then if the stack is empty report an error. Otherwise, pop the stack. If the symbol popped is not the corresponding opening symbol, then report an error. At end of file, if the stack is not empty report an error.

Besides the balancing of the parentheses, brackets, and braces, the Annotation (“/**/”) should be balanced. When a “/*” is found, all the letters behind will be ignored until a “*/” is found. If it is not found at the end of the file, an error will be reported.

Some of the contents of the stack are shown in the figure below.

Tasks

To complete this assessment, you need to define the implementation of class Stack and complete the main.cpp file in which the delimiter matching is defined.

Following is an ordered list of steps that serves as a guide to completing this assessment. Work and test incrementally. Save often.

1. Begin by the creation of the class Stack. You can implement a stack through either an array or a list. But this class should be defined as a template class. And it should contain the following basic operation.

l void Pop(): Pop an element from the top of the stack

l void Push(const T & e): Push this element into the stack.

l T & Top(): Return the top element of the stack.

l bool Isempty() const: If the stack is empty, return true; otherwise return false.

l int Size() const: Return the number of the elements in the stack.

2. Next, create the file main.cpp and complete the implementation of delimiter matching. The detail steps are as follows.

l Get a file name from the command line parameter, which specifies the file name needing delimiter matching. Invoke the delimiterMatching function using the file name.

l Complete the function delimiterMatching, which accepts a string type parameter. This parameter is the file name described as above. This function repeats reading one character from the file and taking it into process until an error appears or at the end of the file.

Submission

Submit only the following.

1. Stack.h - your completed class Stack definition

2. Stack.cpp - if created

3. main.cpp - your completed delimiter matching file

#include<iostream>
#include<fstream>
#include<string>
using namespace std;

template <class T>
class Stack
{
private:
	T *data;//指向栈顶指针
	int size;//栈长度
	int top;
public:
	Stack(int size=0)//构造函数
	{
		this->size=size;
		this->top=0;
		this->data=new T[size];
	}
	~Stack()//析构函数
	{
		size=0;
		top=0;
		delete []data;	
	}
	void Pop()//栈顶元素出栈
	{
		if(!isEmpty())
		{
			top--;
		}
	}
	void Push(const T & item)//入栈
	{
		if(top<size)
		{
			data[top]=item;
			top++;
		}
	}
	T & Top()//获取栈顶元素
	{
		if(!isEmpty())
		{	
			return data[top-1];
		}
	}
	bool isEmpty()
	{
		if(top==0)
		{
			cout<<"Stack is empty"<<endl;
			return true;
		}
		else return false;
	}
	int Size()
	{
		return top;
	}
};
bool delimiterMatching()
{
	cout<<"请向文件输入字符串："<<endl;
	string s;
	cin>>s;
	ofstream out("F:\\test.txt");
	out<<s<<endl;
	out.close();//关闭文件
	ifstream get("F:\\test.txt");
	char string[50];
	get>>string;//获取文件
	int i=0;
	Stack<char> stack(100);
	while(string[i]!='\0')
	{
		//1、判断是否为左括号，是则入栈
		if(string[i]=='('||string[i]=='['||string[i]=='{')
		{
			stack.Push(string[i]);
			i++;
		}
		//2、右括号的情况
		else if(string[i]==')'||string[i]==']'||string[i]=='}')
		{
			if(stack.isEmpty())//如果栈空说明没有左匹配符
			{
				return false;
			}
			else//栈未空
			{
				char temp;
				temp=stack.Top();//获取栈顶元素，匹配的话栈顶元素出栈
				if((string[i]==')'&&temp=='(')||(string[i]=='}'&&temp=='{')||(string[i]==']'&&temp=='['))
				{
					stack.Pop();
					i++;
				}
				else return false;	
			}
		}
		//3、当读到 / 时有可能是注释符的情况
		else if(string[i]=='/')
		{
			if(string[i+1]=='/'&&stack.isEmpty())
				return true;
			else if(string[i+1]=='/'&&!stack.isEmpty())
				return false;
			else if(string[i+1]=='*')
			{
				int flag=0;
				stack.Push(string[i]);
				stack.Push(string[i+1]);
				i=i+2;        //i加2，读取/*后面的字符
				while(string[i]!='\0')
				{
					if(string[i]=='*'&&string[i+1]=='/')
					{
							stack.Pop();
							stack.Pop();
							i=i+2;
							flag=1;
							break;//中断循环
					}
					else
						i++;//未读到*，往后走
				}
				if(flag==0)
					return false;
			}
		}
		//4、读到*/说明而之前没有与之匹配的/*
		else if(string[i]=='*'&&string[i+1]=='/')
			return false;
		//5、往后遍历
		else
		{
			i++;
		}
		if(string[i]=='\0'&&stack.isEmpty())//最终栈空返回true
			return true;
		if(string[i]=='\0'&&!stack.isEmpty())//最终栈非空返回false
			return false;
	}
}

int main()
{
	Stack<int> s(10);
	/*s.Push(10);
	s.Push(20);
	cout<<s.Size()<<endl;
	s.Pop();
	cout<<s.Size()<<endl;
	cout<<s.isEmpty()<<endl;*///Test Stack

	char c='y';
	while(c=='Y'||c=='y')
	{
		if(delimiterMatching())
			cout<<"分隔符匹配成功!"<<endl;
		else
			cout<<"分隔符匹配不成功!"<<endl;
		cout<<"是否继续 （Y/N）"<<endl;
		cin>>c;
	}
	cout<<"退出程序"<<endl;
	return 0;
}