Implementation of the default four functions in class

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By default, the class implements four functions: default constructor, copy constructor, destructor, and = Operator overload.

 

# Include <iostream> Using   Namespace  STD;  Class  Mystring {  Public  : Mystring (  Const   Char * STR = Null); mystring (  Const Mystring & Other ); ~Mystring (); mystring & Operator = ( Const Mystring & Other); showstring ();  Private  :  Char * M_data ;}; mystring :: ~ Mystring () {Delete [] m_data;} mystring: mystring (  Const   Char * Str ){  If (STR =Null) {m_data = New   Char [ 1  ]; * M_data = '  \ 0  '  ;}  Else  {  Int Length = strlen (STR) + 1  ; M_data = New  Char  [Length];  While (* Str! = '  \ 0  '  ) * M_data ++ = * STR ++ ; * M_data = '  \ 0  '  ;} Mystring: mystring (  Const Mystring & Other ){  Int Length = strlen (other. m_data) + 1  ; M_data = New   Char  (Length); strcpy (m_data, other. m_data ); * M_data = '  \ 0  '  ;} Mystring & Mystring :: Operator = ( Const Mystring & Other ){  If (This == & Other ){  Return * This  ;} Delete [] m_data;  Int Length = strlen (other. m_data) + 1  ; M_data = New   Char  [Length]; strcpy (m_data, other. m_data );  Return * This ;} Mystring: showstring () {cout < This -> M_data < Endl ;}  Int Main ( Int Argc, Char ** Argv) {mystring STR;  Char * P = "  Hello Peter  "  ; Mystring DEST (p); DeST. showstring (); Str = DeST; Str. showstring (); Return   0  ;}