Introduction to Programming Lecture 39

Copy Constructor

Review Pointers Pointers References References Memory Allocation Memory Allocation

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

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

References

&

const

Dynamic Memory Allocation

Native Operator new new delete delete

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

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

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

delete [ ] m ;

Assignment

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

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

Member to Member Assignment

m2 = m1

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

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

Copy Constructor

Call by value

Deep Copy Shallow Copy

Matrix ( Matrix & ) ;

Example class String { char * c ; char * c ; public : public : void copy ( char * s ) ; String ( char * data ) ; void print ( ) ; // etc. // 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 1. Define copy constructor 2. Write assignment operator 3. Provide destructor

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