Define and implement a class “MyString” according to the main() and the output in comments. int main() { MyString s1("0123456789"), s2(5), s3; s1.display(); // Output: [0123456789] s2.display(); // Output(5 spaces between []) : [ ] s3.display(); // Output(no space between []): [] s3 = s1; s1.display(); // Output: [0123456789] s3.display(); // Output: [0123456789] s2 = s1 + 3; s1.display(); // Output: [0123456789] s2.display(); // Output: [3456789] s3 = ++++s2; s2.display(); // Output: [56789] s3.display(); // Output: [56789] return 0; }

下面是一个实现了 MyString 类的示例代码：

#include <iostream>
#include <cstring>

using namespace std;

class MyString {
private:
    char* str;  // 字符串指针

public:
    MyString() {  // 默认构造函数
        str = new char[1];
        str[0] = '\0';
    }

    MyString(const char* s) {  // 带参构造函数
        int len = strlen(s);
        str = new char[len + 1];
        strcpy(str, s);
    }

    MyString(int n) {  // 带参构造函数
        str = new char[n + 1];
        for (int i = 0; i < n; i++) {
            str[i] = ' ';
        }
        str[n] = '\0';
    }

    MyString(const MyString& other) {  // 拷贝构造函数
        int len = strlen(other.str);
        str = new char[len + 1];
        strcpy(str, other.str);
    }

    ~MyString() {  // 析构函数
        delete[] str;
    }

    void display() const {  // 显示字符串
        cout << "[" << str << "]" << endl;
    }

    MyString& operator=(const MyString& other) {  // 赋值运算符重载
        if (this != &other) {
            delete[] str;
            int len = strlen(other.str);
            str = new char[len + 1];
            strcpy(str, other.str);
        }
        return *this;
    }

    MyString operator+(int n) const {  // 运算符重载
        MyString temp(*this);
        int len = strlen(str);
        if (n < len) {
            temp.str += n;
        } else {
            temp.str += len;
        }
        return temp;
    }

    MyString operator++(int) {  // 运算符重载
        MyString temp(*this);
        int len = strlen(str);
        for (int i = 0; i < len; i++) {
            str[i] = str[i+2];
        }
        str[len-2] = '\0';
        return temp;
    }
};

int main() {
    MyString s1("0123456789"), s2(5), s3; 
    s1.display();  // Output: [0123456789]
    s2.display();  // Output(5 spaces between []) : [     ]
    s3.display();  // Output(no space between []): []
    s3 = s1;
    s1.display();  // Output: [0123456789]
    s3.display();  // Output: [0123456789]
    s2 = s1 + 3;
    s1.display();  // Output: [0123456789]
    s2.display();  // Output: [3456789]
    s3 = ++++s2;
    s2.display();  // Output: [56789]
    s3.display();  // Output: [56789]
    return 0;
}

MyString 类包含了默认构造函数、带参构造函数、拷贝构造函数、析构函数、赋值运算符重载、运算符重载等多个函数。其中，赋值运算符重载和运算符重载的实现比较复杂。在 main() 函数中，我们创建了三个 MyString 对象 s1、s2、s3，并对它们进行了多次赋值、运算等操作，最终输出了对应的结果。