基于char * 设计一个字符串类MyString，并且具有构造函数、析构函数、复制构造函数，重载运算符“+”，“=”， “+=”， “[]“，尽可能完善它，使之能满足各种需要。

基于char * 设计一个字符串类MyString，并且具有构造函数、析构函数、复制构造函数，重载运算符“+”，“=”， “+=”， “[]"，尽可能完善它，使之能满足各种需要。

#include 
#include 
using namespace std;
class MyString {
     
private:
	char* p;
	int len;
public:
	MyString();
	MyString(int n);
	MyString(const char* temp);
	MyString(const MyString& a);
	~MyString();
	char& operator[](int n);
	MyString& operator=(const MyString& a);
	MyString operator+(const MyString& a);
	MyString& operator+= (const MyString & a);
	void GetLen() {
      cout << "Len: " << len <<  endl; }
	void ShowString() {
     
		int i = 0;
		while (p[i]) {
     
			cout << p[i];
			i++;
		}
		cout << endl;
	}
};
MyString::MyString() {
     
	p = new char[1];
	p[0] = '\0';
	len = 0;
}
MyString::MyString(int n) {
     
	len = n;
	p = new char[n+1];
	for (int i = 0; i <= n; i++)
		p[i] = '\0';
}
MyString::MyString(const char* temp) {
     
	int i;
	len = strlen(temp);
	p = new char[len + 1];
	for (i = 0; i < len; i++) {
     
		p[i] = temp[i];
	}
	p[i] = '\0';
}
MyString::MyString(const MyString& a) {
     
	len = a.len;
	int i;
	p = new char[len + 1];
	for (i = 0; i < len; i++) {
     
		p[i] = a.p[i];
	}
	p[i] = '\0';
}
MyString::~MyString() {
     
	delete [] p;
	len = 0;
}
char& MyString::operator[](int n) {
     

		return p[n];
}
MyString& MyString::operator=(const MyString& a) {
     
	delete[] p;
	len = a.len;
	p = new char[len + 1];
	int i;
	for (i = 0; i < len; i++) {
     
		p[i] = a.p[i];
	}
	p[i] = '\0';
	return *this;
}
MyString MyString::operator+(const MyString& a) {
     
	int total = len + a.len;
	MyString temp(total);
	int i;
	for (i = 0; i < len; i++)
		temp[i] = p[i];
	for (int j = 0; j < a.len; i++, j++)
		temp[i] = a.p[j];
	temp[i] = '\0';

	return temp;
}
MyString& MyString::operator+= (const MyString& a) {
     
	int total = len + a.len;
	MyString temp(total);
	int i;
	for (i = 0; i < len; i++)
		temp[i] = p[i];
	for (int j = 0; j < a.len; i++, j++)
		temp[i] = a.p[j];
	temp[i] = '\0';
	*this = temp;
	return *this;
}
int main() {
     
	MyString str1("Hello");
	cout << "str1:" << endl;
	str1.GetLen();
	str1.ShowString();
	MyString str2("World");
	cout << "str2:" << endl;
	str2.GetLen();
	str2.ShowString();
	MyString str3;
	cout << "str3 = st31 + str2 :" << endl;
	str3 = str1 + str2;
	str3.GetLen();
	str3.ShowString();
	MyString str4;
	cout << "str4 = str3" << endl;
	str4 = str3;
	str4.GetLen();
	str4.ShowString();

	return 0;
}