Introduction to Programming

Introduction to Programming Lecture 39

Copy Constructor

Review • Pointers • References • Memory Allocation

Pointers A pointer is a special type of variable that contain a memory address

Void Pointer • Pointer to an Integer • Pointer to a Character • Pointer to a Float • Pointer to Objects

References

const

Dynamic Memory Allocation

Native Operator • new • delete

Dynamic Memory Allocation int *p ; p = new int ; delete p ;

Dynamic Memory Allocation int *p ; p = new int [ 10 ] ; delete [ ] p ;

Example class Matrix { private : int * m ; int row , col ; public : Matrix ( int rows , int cols ) { m = new int [ rows * cols ] ; } } ;

delete [ ] m ;

Assignment

int i = 0 ; //Initialization int i ; i = 0 ; //Assignment

Matrix m1 , m2 ; …… m2 = m1 ; //Assignment Statement

Member to Member Assignment

m2 = m1

Pointing to the same region in memory int *m of m1 0xefffdad0 mx int *m of m2 0xefffdad0

Copy Constructor

Call by value

Deep Copy Shallow Copy

Matrix ( Matrix & ) ;

Example class String { char * c ; public : void copy ( char * s ) ; String ( char * data ) ; void print ( ) ; // etc. } ;

Example String s1 ( “test1” ) ; String s2 = s1 ; s1.copy ( “this is a test” ) ; s2.print ( ) ;

int i ; i = 10 ; i = i ;

Matrix m2 ( m1 ) ; Matrix m2 = m1 ;

Rules For dynamic memory allocation • Define copy constructor • Write assignment operator • Provide destructor

What have we covered today • Review of pointers • Dynamic memory allocation • new • Delete • For memory allocation in classes we must provide • Constructor • Copy constructor • Assignment operator • destructor

Introduction to Programming