Inheritance

1
Inheritance Dynamic Memory Allocation

• Suppose base class uses dynamic memory
  allocation.
• If derived class doesnt use dynamic memory
  allocation then no further step is needed,
  otherwise we should do sth for it.

2

• class baseDMA
• private
• char label
• int rating
• public
• baseDMA ( const char lnull, int r0)
• baseDMA (const baseDMA rs)
• virtual baseDMA()
• baseDMA operator (const baseDMA rs)

3

• class lacksDMA public baseDMA
• private
• char color 40
• public
• If we dont define destructor, the compiler
  defines the default one which calls the
  base-class destructor after executing its own
  code.

4

• Copy constructor does memberwise copying which
  is fine for lacksDMA member.
• The same for assignment operator.

5

• class baseDMA
• private
• char label
• int rating
• class hasDMA public baseDMA
• private
• char style
• public
• .
• baseDMA baseDMA()
• delete label
• hasDMA hasDMA()
• delete style

6

• baseDMA baseDMA(const baseDMA rs)
• labelnew charstrlen(rs.label)1
• strcpy(label, rs.label)
• ratingrs.rating
• hasDMA(const hasDMA hs) baseDAM(hs)
• stylenew charstrlen(hs.style)1
• strcpy(label, hs.style)
• // the baseDMA constructor uses the baseDMA
  portion of the hasDMA argument to construct the
  basDMA portion of the new object

7

• baseDMA baseDMAoperator(const baseDMA rs)
• if (this rs )
• return this
• delete label
• labelnew charstrlen(rs.label)1
• strcpy(label, rs.label)
• ratingrs.rating
• return this

8

• hasDMA hasDMAoperator(const hasDMA hs)
• if (this hs )
• return this
• baseDMA operator(hs)
• //copy base portion
• stylenew charstrlen(hs.style)1
• strcpy(style, hs.style)
• return this

9

• ifndef DAM_H_
• define DAM_H_
• class baseDMA
• private
• char label
• int rating
• public
• baseDMA ( const char l"null", int r0)
• baseDMA (const baseDMA rs)
• virtual baseDMA()
• baseDMA operator(const baseDMA rs)
• friend ostream operatorltlt(ostream os,
  const baseDMA rs)

10

• class lacksDMA public baseDMA
• private
• enum COL_LEN 40
• char colorCOL_LEN
• public
• lacksDMA (const char c "black", const char l
  "null",
• int r0)
• lacksDMA (const char c , const baseDMA rs )
• friend ostream operator ltlt ( ostream os ,
  const lacksDMA rs)

11

• class hasDMA public baseDMA
• private
• char style
• public
• hasDMA (const char s "none", const char l
  "null",
• int r0)
• hasDMA (const char s , const baseDMA rs )
• hasDMA (const hasDMA rs )
• hasDMA()
• hasDMA operator(const hasDMA rs)
• friend ostream operator ltlt ( ostream os ,
  const hasDMA rs)
• endif

12

• include ltiostream.hgt
• include "dam.h"
• includeltcstringgt
• baseDMA baseDMA(const char l , int r)
• labelnew charstrlen(l)1
• strcpy(label, l)
• ratingr
• baseDMA baseDMA(const baseDMA rs)
• labelnew charstrlen(rs.label)1
• strcpy(label, rs.label)
• ratingrs.rating

13

• baseDMA baseDMA ()
• delete label
• baseDMA baseDMAoperator(const baseDMA rs)
• if (this rs )
• return this
• delete label
• labelnew charstrlen(rs.label)1
• strcpy(label, rs.label)
• ratingrs.rating
• return this

14

• ostream operator ltlt (ostream os, const baseDMA
  rs)
• osltlt"label "ltltrs.labelltltendl
• osltlt"rating "ltltrs.ratingltltendl
• return os
• lacksDMA lacksDMA (const char c, const char
  l,
• int r) baseDMA(l,r)
• strncpy(color, c, 39)
• color39'\0'

15

• lacksDMA lacksDMA (const char c, const baseDMA
  rs) baseDMA(rs)
• strncpy(color, c, COL_LEN-1)
• colorCOL_LEN-1\0
• ostream operator ltlt (ostream os, const lacksDMA
  ls)
• osltlt(const baseDMA ) ls
• osltltcolor ltltls.colorltltendl
• return os

16

• Friend function of lacksDMA has access to color (
  member of lacksDMA) but this friend function has
  no access to to label of baseDMA, so we use type
  casting.
• We use base portion of hs to call friend
  function of baseDMA ( here coutltlt).

17

• hasDMA hasDMA (const char s, const char l ,
  int r) baseDMA (l,r)
• stylenew char strlen(s)1
• strcpy(style,s)
• hasDMA hasDMA (const char s, const baseDMA
  rs) baseDMA (rs)
• stylenew char strlen(s)1
• strcpy(style,s)

18

• hasDMA hasDMA(const hasDMA hs )
• baseDMA(hs) // call base class copy constructor
  
• stylenew char strlen(hs.style)1
• strcpy(style,hs.style)
• hasDMA hasDMA()
• delete style

19

• hasDMA hasDMAoperator(const hasDMA hs)
• if (this hs )
• return this
• baseDMAoperator(hs) // copy base portion
• stylenew charstrlen(hs.style)1
• strcpy(style, hs.style)
• return this

20

• ostream operator ltlt (ostream os, const hasDMA
  hs)
• osltlt(const baseDMA ) hs
• osltlt"Style "ltlths.styleltltendl
• return os

21

• includeltiostream.hgt include dam.h
• int main()
• baseDMA shirt(Portability, 8)
• lacksDMA balloon( red, Blimpo,4)
• hasDMA map(Mercator, Buffalo Keys,5)
• coutltltshirtltltendl
• coutltltballoonltltendl
• coutltltmapltltendl
• lacksDMA balloon2(balloon)
• hasDMA map2
• map2map
• coutltltballoon2ltltendl
• coutltltmap2ltltendl
• return 0

22

• label Portability
• Rating 8
• Label Blimpo
• Rating4
• Color red
• Label Buffalo Keys
• Rating5
• Style Mercator
• Label Blimpo
• Rating4
• Color red
• Label Buffalo Keys
• Rating 5
• Style Mercator