强化练习-string类的实现

梦里梦外; 2022-03-18 12:36 159阅读 0赞

MyString.h

#pragma once
    #include <iostream>
    using namespace std;
    
    
    class Mystring
    { 
    public:
    	Mystring();
    	Mystring(const char* str);
    	Mystring(const Mystring& another);
    	~Mystring();
    
    
    	char& operator[](int index);
    	friend ostream& operator<<(ostream& os, const Mystring& str);
    	friend istream& operator>>(istream& is,  Mystring& str);
    	Mystring& operator=(const char* str);
    	Mystring& operator=(const Mystring& str);
    	bool operator==(const Mystring& another);
    	Mystring operator+(const Mystring& another);
    
    
    private:
    	int m_length;
    	char* m_ptr;
    };

MyString.cpp

#include "stdafx.h"
    #include "MyString.h"
    
    Mystring::Mystring()
    { 
    	m_length = 0;
    	m_ptr = NULL;
    }
    
    
    Mystring::Mystring(const char* str)
    { 
    	int len = strlen(str);
    	if (len > 0)
    	{ 
    		m_length = len;
    		m_ptr = new char[len+1];
    		m_ptr[len] = 0;
    		memcpy(m_ptr, str, len);
    	}
    
    }
    
    
    Mystring::Mystring(const Mystring& another)
    { 
    	int len = another.m_length;
    	if (len > 0)
    	{ 
    		m_length = len;
    		m_ptr = new char[len + 1];
    		m_ptr[len] = 0;
    		memcpy(m_ptr, another.m_ptr, len);
    	}
    
    
    }
    
    
    Mystring::~Mystring()
    { 
    	if (m_ptr != NULL)
    	{ 
    		delete m_ptr;
    		m_ptr = NULL;
    		m_length = 0;
    	}
    }
    
    
    char& Mystring::operator[](int index)
    { 
    	return m_ptr[index];
    }
    
    
    ostream& operator<<(ostream& os, const Mystring& str)
    { 
    	os << str.m_ptr;
    
    	return os;
    }
    
    
    istream& operator>>(istream& is,  Mystring& str)
    { 
    	if (str.m_length == 0&& str.m_ptr==NULL)
    	{ 
    		char string_tmp[100] = {  0 };
    		cin >> string_tmp;
    		int len = strlen(string_tmp);
    		str.m_length = len;
    		str.m_ptr = new char[len + 1];
    		str.m_ptr[len] = 0;
    		memcpy(str.m_ptr, string_tmp, len);
    	}
    	return is;
    }
    
    
    
    Mystring& Mystring::operator=(const char* str)
    { 
    	int len = strlen(str);
    	if (len > 0)
    	{ 
    		delete[] m_ptr; //把以前释放
    		m_length = len;
    		m_ptr = new char[len + 1];
    		m_ptr[len] = 0;
    		memcpy(m_ptr, str, len);
    		return *this;
    	}
    }
    
    
    Mystring& Mystring::operator=(const Mystring& str)
    { 
    	if (this == &str) return *this;
    	int len = str.m_length;
    	if (len > 0)
    	{ 
    		delete[] m_ptr; //把以前释放
    		m_length = len;
    		m_ptr = new char[len + 1];
    		m_ptr[len] = 0;
    		memcpy(m_ptr, str.m_ptr, len);
    		return *this;
    	}
    }
    
    
    
    
    bool Mystring::operator==(const Mystring& another)
    { 
    	if (this == &another)return true;
    	int len = another.m_length;
    	if (m_length == len && len > 0)
    	{ 
    		for (int i = 0; i < len; i++)
    		{ 
    			if (m_ptr[i] != another.m_ptr[i])
    				return false;
    
    		}
    		return true;
    	}
    	else
    		return false;
    }
    
    
    
    
    Mystring Mystring::operator+(const Mystring& another)
    { 
    	Mystring tmp;
    	if (another.m_length == 0)
    		return *this;
    	else
    	{ 
    		int all_len = m_length + another.m_length;
    		char* new_ptr = new char [all_len + 1];
    		new_ptr[all_len] = 0;
    		memcpy(new_ptr, m_ptr, m_length);
    		memcpy(new_ptr + m_length, another.m_ptr, another.m_length);
    		
    		tmp.m_ptr = new_ptr;
    		tmp.m_length = all_len;
    		return tmp;
    	}
    
    }

user.cpp

#include "stdafx.h"
    #include "MyString.h"
    
    int main()
    { 
    
    	Mystring str1("julian");
    
    	Mystring str2;
    	cin >> str2;
    	cout << str1 << " " << str2 << endl;
    
    	str2 = str1;
    	cout << str2 << endl;
    	str2 = "fuck";
    	cout << str2 << endl;
    
    	Mystring str3(str1);
    	Mystring str4 = "mark";
    	if (str3 == str4)
    		cout << "same" << endl;
    	else
    		cout << "no same" << endl;
    
    	
    	if (str3 == str1)
    		cout << "same" << endl;
    	else
    		cout << "no same" << endl;
    
    	str4[0] = 'a';
    	cout << str4 << endl;
    
    	Mystring str5 = str1 + str4;
    	
    	str5[0] = 'w';
    
    	cout << str5 << endl;
    	cout << str1 << endl;
    	cout << str5 + str1 + str2 << endl;
    
    
    
        return 0;
    }

结果输入：kerr  
输出：  
![在这里插入图片描述][20190220212412439.png]

[20190220212412439.png]: /images/20220318/19bc833a3c584797a119a6a6e3216b3a.png