Write string-like constructor, copy constructor, and destructor

The prototype of the string class is as follows:

Class string
{
Public:
String (const char * STR = NULL );
String (const string & other );
~ String (void );
String & operator = (const string & other );
PRIVATE:
Char * m_data;
};

Implementation of the string class
String ::~ String ()
{
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 [Length + 1];
Strcpy (m_data, other. m_data );
}
String & string: Operator = (const string & other)
{
If (this = & other)
Return * this;
 
Delete [] m_data;

Int length = sizeof (other. m_data );
M_data = new [Length + 1];
Strcpy (m_data, other. m_data );

Return * this;
}