手动实现String类

/********
 * author:upupupCoder
 * time:2022/3/30
 * Website:https://home.cnblogs.com/u/EmbeddedChicken
 * ******/
#include
#include<string.h>
using namespace std;
class MyString
{
    friend ostream& operator<<(ostream&out,const MyString &str);
private:
    char *m_data;
public:
    MyString(const char *str=NULL);
    MyString(const MyString&other);
    MyString&operator=(const MyString &other);
    MyString operator+(const MyString &other);
    ~MyString();
};

MyString::MyString(const char *str)
{
    if(str)
    {
        int length = strlen(str);
        this->m_data = new char[length+1];
        strcpy(this->m_data,str);
    }
    else
    {
        this->m_data = new char[1];
        *this->m_data = '\0';
    }
}

MyString::MyString(const MyString&other)
{
    if(other.m_data)
    {
        int length = strlen(other.m_data);
        this->m_data = new char[length+1];
        strcpy(this->m_data,other.m_data);
    }
    else
    {
        this->m_data = new char[1];
        *this->m_data = '\0';
    }
}

MyString::~MyString()
{
    if(this->m_data)
    {
        delete[] this->m_data;
    }
}
MyString MyString::operator+(const MyString&other)
{
    char *str = new char[strlen(other.m_data)+strlen(this->m_data)+1];
    strcpy(str,this->m_data);
    strcat(str,other.m_data);
    return str;
}
MyString &MyString::operator=(const MyString&other)
{
    if(&other!=this)
    {
        delete[]this->m_data;
        int length = strlen(other.m_data);
        this->m_data=new char[length+1];
        strcpy(this->m_data,other.m_data);
    }
    return *this;
}

ostream& operator<<(ostream &out,const MyString&str)
{
    out<<str.m_data;
    return out;
}
int main()
{
    MyString s1;
    MyString s2="123456";
    MyString s3=s2;
    MyString s4("ahhadkl");
    MyString s5=s3+s2;
    cout<<' '<' '<' '<' '<' '<endl;
    return 0;
}