Introduction of Programming Lecture 28

Today’s Lecture How memory allocation is done in How memory allocation is done in C++ C++ How is it different from C style How is it different from C style Advantages of memory allocation in Advantages of memory allocation in C++ C++ Uses of memory allocation Uses of memory allocation – Classes – Objects

Pointers to a data structure

Pointers to a class

->

Memory Allocation

malloc ( ) ; calloc ( ) ; realloc ( ) ;

malloc ( 10 * ( sizeof ( int ) ) ) ;

free ( )

new

new int ;

int * iptr ; iptr = new int ; Example

new char ; new double ; Example

delete

int * iptr ; iptr = new int ; delete iptr ; Example

int * iptr ; iptr = new int [ 10 ] ; Example

new data_type [ Number_of_locations ] ; new double [ 10 ] ; Example

int *iptr ; iptr = new int [ 10 ] ; delete iptr ; Example

Date *dptr ; dptr is a pointer to an object of type date Example

dptr = new Date ;

main ( ) { Date mydate ; cout<< sizeof ( mydate ) ; } Example

int *iptr ; iptr = new int [ 10 ] ; Example

Date *dptr ; dptr = new Date [ 10 ] ; Example

Date date1, *dptr ; date1.setDate ( ) ; dptr = new Date ; dptr = new Date ; dptr ->setDate ( ); dptr.setDate ( ) ; Wrong Example

Protected

Destructor

Allocate enough space for Allocate enough space for the new data the new data Populate that space Populate that space Delete the previous space Delete the previous space Point the new space to the Point the new space to the pointer pointing to the pointer pointing to the original data original data

char *name =new char [ string_length ]

delete [ ] name

delete [ ] pointer_name

main ( ) { Date mydate ( “ ” ) ; Date mydate ( “ ” ) ; mydate.display ( ) ; } Example

Messages

Method