Interview question 6: Write string-like constructor, copy constructor, destructor, and assignment function

The prototype of the known class string is:

Class string

{

Public:

String (const char * STR = NULL); // common Constructor

String (const string & other); // copy the constructor

~ String (void); // destructor

String & operator = (const string & other); // value assignment function

PRIVATE:

Char * m_data; // used to save strings

};

Write the above four functions of string

 

/* Destructor */

String ::~ String (void)

{

Delete [] m_data; // because m_data is an internal data type, you can also write it as delete m_data;

}

 

/* Common constructor */

String: string (const char * Str)

{

If (STR = NULL)

{

M_data = new char [1];

* M_data = '\ 0 ';

}

Else

{

Int Len = strlen (STR );

M_data = new char [Len + 1];

Strcpy (m_data, STR );

}

}

/* Copy the constructor */

String: string (const string & other)

{

Int Len = strlen (other. m_data );

M_data = new char [Len + 1]; // m_data is directed only to the applied space. It is only a pointer before it is applied, not to the specified memory space.

If (m_data! = NULL)

Strcpy (m_data, other. m_data );

}

/* Value assignment function */

String & string: Operator = (const string & other)

{

If (this = & other)

Return * this;

Delete [] m_data; // release the original memory resource

Int Len = strlen (other. m_data );

M_data = new char [Len + 1]; // allocate new memory resources

If (m_data! = NULL)

Strcpy (m_data, other. m_data );

Return * This; // return the reference of this object

}