添加>重载

好的，以下是添加了 `>` 运算符重载的代码：

#include <iostream>
#include <cstring>

class MyString {
public:
    MyString() : ptr(nullptr), len(0) {}
    MyString(const char* str) {
        len = std::strlen(str);
        ptr = new char[len + 1];
        std::strcpy(ptr, str);
    }
    MyString(const MyString& other) {
        len = other.len;
        ptr = new char[len + 1];
        std::strcpy(ptr, other.ptr);
    }
    ~MyString() {
        if (ptr != nullptr) {
            delete[] ptr;
            ptr = nullptr;
        }
    }

    MyString& operator=(const MyString& rhs) {
        if (this != &rhs) {
            if (ptr != nullptr) {
                delete[] ptr;
            }
            len = rhs.len;
            ptr = new char[len + 1];
            std::strcpy(ptr, rhs.ptr);
        }
        return *this;
    }

    MyString operator+(const MyString& rhs) const {
        MyString result;
        result.len = len + rhs.len;
        result.ptr = new char[result.len + 1];
        std::strcpy(result.ptr, ptr);
        std::strcat(result.ptr, rhs.ptr);
        return result;
    }

    MyString& operator+=(const MyString& rhs) {
        len += rhs.len;
        char* temp = new char[len + 1];
        std::strcpy(temp, ptr);
        std::strcat(temp, rhs.ptr);
        delete[] ptr;
        ptr = temp;
        return *this;
    }

    char& operator[](int index) {
        return ptr[index];
    }

    void insert(const char* str, int pos) {
        int str_len = std::strlen(str);
        char* temp = new char[len + str_len + 1];
        std::strncpy(temp, ptr, pos);
        std::strcpy(temp + pos, str);
        std::strcpy(temp + pos + str_len, ptr + pos);
        delete[] ptr;
        ptr = temp;
        len += str_len;
    }

    bool operator>(const MyString& rhs) const {
        return std::strcmp(ptr, rhs.ptr) > 0;
    }

    friend std::ostream& operator<<(std::ostream& os, const MyString& str);

private:
    char* ptr;
    int len;
};

std::ostream& operator<<(std::ostream& os, const MyString& str) {
    os << str.ptr;
    return os;
}

int main() {
    MyString s1 = "Hello";
    MyString s2 = "World";
    std::cout << s1 << std::endl;
    std::cout << s2 << std::endl;
    s1 += s2;
    std::cout << s1 << std::endl;
    s1.insert(" ", 5);
    std::cout << s1 << std::endl;
    std::cout << s1[11] << std::endl;
    std::cout << (s1 > s2) << std::endl;
    return 0;
}

在这里，我们重载了 `>` 运算符，使得两个字符串对象可以进行比较，如果左边的字符串对象大于右边的字符串对象，则返回 `true`，否则返回 `false`。在 `operator>` 中，我们使用了 `strcmp` 函数来比较两个字符串的字典序大小。