C++梁哥笔记day13 | 我的日常分享

C++梁哥笔记day13

发表于2021-01-04更新于2021-01-04字数统计468阅读时长5分

类与对象

一、自定义一个string类myString

对运算符重载以及之前所学的复习

myString.h

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#ifndef MYSTRING_H
#define MYSTRING_H
#include <iostream>
using namespace std;

class myString
{
    friend ostream& operator<<(ostream& out,myString ob);
private:
    char *str;
    int m_length;
public:
    myString();
    myString(const char *str);
    ~myString();
    myString(const myString &ob);
    int length();
    myString& operator=(myString &ob);
};

#endif // MYSTRING_H

myString.cpp

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#include "mystring.h"
#include<iostream>
#include<string.h>

myString::myString()
{
    this->str = NULL;
    this->m_length = 0;
    cout<<"无参构造方法"<<endl;
}

myString::myString(const char *str)
{
    this->str = new char[strlen(str) + 1];
    strcpy(this->str,str);
    this->m_length = strlen(str);
    cout<<"构造方法myString::myString(const char *str)"<<endl;
}

myString::~myString()
{
    if(this->str != NULL){
        delete [] this->str;
        this->str = NULL;
    }
    cout<<"析构函数~myString()"<<endl;
}

myString::myString(const myString &ob)
{
    this->str = new char[ob.m_length + 1];
    strcpy(this->str,ob.str);
    this->m_length = ob.m_length;
    cout<<"拷贝构造函数myString(const myString &ob)"<<endl;
}

int myString::length()
{
    return this->m_length;
}

myString &myString::operator=(myString &ob)
{
    if(this->str != NULL){
        delete [] this->str;
        this->str = NULL;
    }
    this->str = new char[ob.m_length + 1];
    strcpy(this->str,ob.str);
    this->m_length = ob.m_length;
}

ostream& operator<<(ostream& out,myString ob){
    out<<ob.str;
    return out;
}

main.cpp

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

int main(int argc, char *argv[])
{
    myString str1("hello str1");
    cout<<"str1:"<<str1<<",length:"<<str1.length()<<endl;

    myString str2 = str1;
    cout<<"str2:"<<str2<<",length:"<<str2.length()<<endl;

    myString str3;
    str3 = str1;
    cout<<"str3:"<<str3<<",length:"<<str3.length()<<endl;

    myString str4 = "hello str4";//隐式转化调用有参构造str4("hello str4") --> str4 = myString("hello str4")
    cout<<"str4:"<<str4<<",length:"<<str4.length()<<endl;
    return 0;
}

运行结果：
图片

未写完整，还有一些功能可以去完善