C++day5 - 技术栈

一、思维导图

二、myString

cpp 复制代码

#ifndef MYSTRING_H
#define MYSTRING_H
#include <iostream>
#include<cstring>

using namespace std;
class myString
{

public:
    //无参构造
    myString();
    //有参构造
    myString(const char *str);
    //析构函数
    ~myString();
    //判空函数
    bool is_empty();
    //strlen函数
    int strlen();
    //get_size
    int get_capacity();
    //c_str函数
    const char* c_str();
    //at函数
    char& at(int index);
    //clear函数
    void clear();

    //二倍扩容
    void expend();

    //data函数
    char* data();

    //operator =
    void operator=(const myString &other);

    //operator +
    myString& operator+(const myString &other);

    //operator []
    char& operator[](int index);

    //operator +=
    myString& operator+=(const myString &other);

    //operator ==字符内容相等即可
    bool operator==(const myString &other);


    //operator != 字符内容不相等即可
    bool operator!=(const myString &other);

    //operator > 字符内容大于即可
    bool operator>(const myString &other);

    //operator >= 字符内容大于等于即可
    bool operator>=(const myString &other);

    //operator < 字符内容小于即可
    bool operator<(const myString &other);

    //operator <= 字符内容小于等于即可
    bool operator<=(const myString &other);


    //push_back,末尾添加字符
    void push_back(const char &other);


    //push_back,末尾删除字符
    void pop_back();

private:
    char *str;          //记录c风格的字符串
    int len;            //记录字符串的实际长度
    int capacity;           //记录String在堆区申请的空间大小

    //将赋值运算符重载函数，设置成友元函数
    friend ostream & operator<<(ostream &mycout, const myString &value);

    friend istream & operator>>(istream &mycin,myString &value);

};

#endif // MYSTRING_H

cpp 复制代码

#include"myString.h"
//无参构造
myString::myString():capacity(10),len(0)
{
    str = new char[capacity];       //构造出一个默认长度为10的字符串
    str[0] = '\0';
}
//有参构造
myString::myString(const char *str)
{
    capacity =10;
    this->str = new char[capacity];

    int count = 0;
    char* ptr =(char *)str;
    while(*ptr != '\0')
    {
        ptr++;
        count++;
        if(count >= capacity)
            expend();
    }
    strcpy(this->str,str);
    len = count;
}
//析构函数
myString::~myString()
{
    delete[] str;
    cout<<"空间释放成功\n"<<endl;
}
//判空函数
bool myString::is_empty()
{
    return len<=0?1:0;
}
//strlen函数
int myString::strlen()
{
    return len;
}
//get_size
int myString::get_capacity()
{
    return capacity;
}
//c_str函数
const char* myString::c_str()
{
    return str;
}
//at函数
char& myString::at(int index)
{
    if(index<0 || index>= len)
    {
        cout <<"输入错误"<<endl;
    }
    char &str = this->str[index];
    return str;
}

//data函数,返回字符串首字符地址
char* myString::data()
{
    return this->str;
}
//二倍扩容
void myString::expend()
{
    char* temp = new char [capacity*2];
    strcpy(temp, str); // 将旧字符串复制到新内存空间
    delete[] str;
    str = temp;
    capacity *= 2;
}

//clear函数
void myString::clear()
{
    this->len = 0;

}

//push_back,末尾添加字符
void myString::push_back(const char &other)
{
    //判断大小
    if((len+1) == this->capacity)
    {
        //二倍扩容
        this->expend();
    }
    str[len] = other;
    this->len++;
}

//push_back,末尾删除字符
void myString::pop_back()
{
    str[len-1] = '\0';
    this->len--;
}


//operator +=
myString& myString::operator+=(const myString &other)
{
    while (this->capacity< (this->len+other.len)) {
        //二倍扩容
        this->expend();
    }
    strcat(this->str,other.str);
    this->len = this->len+other.len;

    return *this;
}

//operator =
void myString::operator=(const myString &other)
{
   this->capacity = other.capacity;
   this->len = other.len;
   strcpy(this->str,other.str);
   this->len = other.len;
}

//operator +
myString& myString::operator+(const myString &other)
{
    static myString Temp;
    while (Temp.capacity< (this->len+other.len)) {
        //二倍扩容
        Temp.expend();
    }
    strcpy(Temp.str,this->str);
    strcat(Temp.str,other.str);
    Temp.len = this->len+other.len;

    return Temp;
}

//operator == 字符内容相等即可
bool myString::operator==(const myString &other)
{
    if(strcmp(this->str,other.str) == 0)
    {
        return true;
    }else
    {
        return false;
    }
}

//operator != 字符内容不相等即可
bool myString::operator!=(const myString &other)
{
    if(strcmp(this->str,other.str) != 0)
    {
        return true;
    }else
    {
        return false;
    }
}

//operator > 字符内容大于即可
bool myString::operator>(const myString &other)
{
    if(strcmp(this->str,other.str) > 0)
    {
        return true;
    }else
    {
        return false;
    }
}

//operator >= 字符内容大于等于即可
bool myString::operator>=(const myString &other)
{
    if(strcmp(this->str,other.str) >= 0)
    {
        return true;
    }else
    {
        return false;
    }
}


//operator < 字符内容小于即可
bool myString::operator<(const myString &other)
{
    if(strcmp(this->str,other.str) < 0)
    {
        return true;
    }else
    {
        return false;
    }
}

//operator <= 字符内容小于等于即可
bool myString::operator<=(const myString &other)
{
    if(strcmp(this->str,other.str) <= 0)
    {
        return true;
    }else
    {
        return false;
    }
}


//自定义输出运算符重载函数：只能实现全局函数版
ostream & operator<<(ostream &mycout, const myString &value)
{
    //输出内容
    if(value.len > 0)
    {
        mycout<<value.str;
    }
    //返回左操作数自身
    return mycout;
}


//自定义插入运算符重载函数：只能实现全局函数版
istream& operator>>(istream &mycin, myString &value)
{
    //输入内容
    char temp[1024] = {0};
    mycin>>temp;
    while(value.len  < strlen(temp))
    {
        //二倍扩容
        value.expend();
    }
    strcpy(value.str,temp);
    value.len = strlen(temp);
    //返回左操作数自身
    return mycin;
}

//operator []
char& myString::operator[](int index)
{
    if(index<0 || index>= this->len)
    {
        cout <<"输入错误"<<endl;
    }
    char &str = this->str[index];
    return str;
}

cpp 复制代码

#include"myString.h"

int main()
{
    //实例化一个myString的str，调用了myString的无参构造
    myString str1;
    cout<<"str1_size ="<<str1.get_capacity()<<endl; //输出默认size
    cout<<"str1_len ="<<str1.strlen()<<endl;   //输出默认len


    //有参构造
    myString str2("hello world");
    cout<<"str2_size ="<<str2.get_capacity()<<endl; //输出size
    cout<<"str2_len ="<<str2.strlen()<<endl;   //输出len

    //c_str函数
    const char *str = str2.c_str();
    cout<<"str ="<<str<<endl;

    //at函数
    cout<<"str[8] ="<<str[8]<<endl;

    //operator =
    str1 = str2;
    //cout<<"str1 ="<<str1<<endl;

    //operator +
    myString str3 = str1 + str2;
    cout<<"str1 ="<<str1<<endl;
    cout<<"str2 ="<<str2<<endl;
    cout<<"str3 ="<<str3<<endl;

    //push_back,末尾添加字符
    str1.push_back('H');
    cout<<"str1 ="<<str1<<endl;

    //push_back,末尾删除字符
    str1.pop_back();
    cout<<"str1 ="<<str1<<endl;

    //operator == 字符内容相等即可
    if(str1 == str2)
    {
        cout<<"str1 == str2"<<endl;
    }

    //operator +=
    str3 += str1;
    cout<<"str3 ="<<str3<<endl;

    //operator >>
    cout<<"请输入str1"<<endl;
    cin>>str1;
    cout<<"str1 ="<<str1<<endl;
    cout<<"str1.len ="<<str1.strlen()<<endl;

    //operator []
    cout<<"str1[2] ="<<str1[2]<<endl;

    return 0;
}