4月21日 C++

#include <iostream>

#include <cstring>

using namespace std;

class My_string

public:

    //无参构造

    My_string(); //默认给32字节

    //有参构造

    My_string(char* str);

    //拷贝构造

    My_string(const My_string &other);

    //拷贝赋值

    My_string &operator=(const My_string &other);

    //判空

    bool empty();

    //返回长度

    unsigned long size_str();

    //将C++风格转化成C风格

    const char *back_str();

    //at

    char at_str(unsigned int pos);

    //指定访问某个字符

    char &operator[](unsigned int pos);

    //strcat

    My_string &operator+(My_string &other);

    //strcmp

    bool operator>(My_string &other);

    //析构函数

    ~My_string();

private:

    char* _str;

    unsigned long size;

};

//无参构造

My_string::My_string():size(32) //默认给32字节

    _str = new char[this->size];

    strcpy(_str, "");

//有参构造

My_string::My_string(char* str)

    this->size = strlen(str)+1;

    _str = new char[size];

    strcpy(_str, str);

//拷贝构造

My_string::My_string(const My_string &other):size(other.size)

    _str = new char[this->size];

    strcpy(this->_str, other._str);

//拷贝赋值

//函数名之前加作用域!!!!!!!!

My_string &My_string::operator=(const My_string &other)

    this->size = other.size;

    _str = new char[this->size];

    strcpy(_str, other._str);

    return *this;

//判空

bool My_string::empty()

    return strlen(this->_str) == 0?1 : 0;

//返回长度

unsigned long My_string::size_str()

    return this->size-1;

//将C++风格转化成C风格

const char *My_string::back_str()

    return this->_str;

//at

char My_string::at_str(unsigned int pos)

    if (pos > this->size)

        cout << "段错误" << endl;

    return *(this->_str + pos);

//指定访问某个字符

char &My_string::operator[](unsigned int pos)

    if (pos > this->size)

        cout << "越界" << endl;

    return *(this->_str+pos);

//strcat

My_string &My_string::operator+(My_string &other)

    if (0 == other.size || 0 == this->size)

        cout << "error" << endl;

    char *temp = new char[this->size + other.size - 1]; //两个字符串结尾\0

    for (unsigned int i = 0 ; i < this->size-1 ; i++)

        *(temp+i) = *(this->_str+i);

    for (unsigned int i = this->size-1 ; i < this->size + other.size - 1 ; i++)

        *(temp+i) = *(this->_str+i);

    this->_str = temp;

    temp = nullptr;

    this->size = this->size + other.size - 1;

    return *this;

//strcmp >

bool My_string::operator>(My_string &other)

    unsigned int temp = this->size > other.size ? this->size : other.size;

    for (unsigned int i = 0 ; i < temp ; i++)

        return *(this->_str + i) > *(other._str + i) ? 1 : 0;

    return 0;

//strcmp <

bool My_string::operator>(My_string &other)

    unsigned int temp = this->size > other.size ? this->size : other.size;

    for (unsigned int i = 0 ; i < temp ; i++)

        return *(this->_str + i) < *(other._str + i) ? 1 : 0;

    return 0;

//析构函数

My_string::~My_string()

    delete[] _str;

    _str = nullptr;

int main()

    return 0;

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