编写类String的构造函数，析构函数和赋值函数

已知类String的原型

class String

{

public:

String(const char *str = NULL);

String(const String &other);

~String(void);

String &operate = (const String &other);

private:

char *m_data;

}

String::~String(void)

{

delete [] m_data;

//由于m_data是内部数据类型，也可以写成delete m_data;

}

String::String(const char *str)

{

if (str == NULL)

{

m_data = new char[1];

*m_data = '/0';

}

else

{

int length = strlen(str);

m_data = new char[length + 1];

strcpy(m_data, str);

}

}

String::String(const String &other)

{

int length = strlen(other.m_data);

m_data = new char[length + 1];

strcpy(m_data, other.m_data);

}

String &String::operate = (const String &other)

{

 

}