The realization of String class of C + + pen Test __c++

This is often asked or tested during an interview or written test.

The prototype for the known class string is:

Class string
{public
:
	string (const char *STR = NULL);//Normal constructor  
	string (const string &other); Copy constructor  
	~string (void);/destructor  
	string & operator = (const string &other);//Assignment Function  
private:
	Char *m _data;//is used to save the string  
};

Please write the above 4 functions of string.

Normal constructor  
string::string (const char *str)
{
	if (str = NULL)
	{
		m_data = new char[1];// Score points: Automatically apply to empty strings to store the end of the flag ' ", plus points: the m_data plus null to judge  
		*m_data = '"
	;}
	else
	{
		int length = strlen (str);
		m_data = new Char[length + 1];//better
		strcpy (m_data, str) If you can add NULL;


The destructor of String  
string::~string (void)
{
	delete[] m_data;//or delete m_data;  
}


Copy constructor  
string::string (const String &other)//score points: The input parameter is a const type  
{		 
	int length = strlen (other.m_data );
	m_data = new Char[length + 1];//better  
	strcpy (m_data, other.m_data) If it can be added with NULL
;


Assignment function  
string & string::operator = (const string &other)//score point: The input parameter is a const type  
{
	if (this = = &oth ER)//score point: Check the value of return  
		*this; 
	if (m_data)
	    delete[] m_data;//score point: Frees the original memory resource  
	int length = strlen (other.m_data);
	m_data = new Char[length + 1];//plus points: m_data plus null to Judge  
	strcpy (M_data, other.m_data);
	Return *this;//score point: Returns a reference to this object    
}

Analysis: The interviewer who can accurately write the constructors of string classes, copy constructors, assignment functions and destructors has at least 60% of the basic skills of C + +.
In this class include the pointer class member variable m_data, when the class includes pointer class member variable, must overload its copy constructors, assignment functions and destructors, this is both the basic requirements of C + + programmers, but also "effective C + +" Special emphasis on the terms.

Carefully learn this class, pay special attention to the point of scoring points and add points of significance, so that have more than 60% of C + + basic skills.

Original link: http://www.cnblogs.com/jwyue0520/archive/2012/12/03/2800160.html