Data Structure

1
Data Structure Algorithm

• Pointer

2
Introduction to Pointer
include ltiostreamgt using namespace std int
main() int i 10 cout ltlt i ltlt "\n" cout
ltlt i ltlt "\n" return 0

• As a starting point, consider the simple C code
  above

3
Introduction to Pointer
include ltiostreamgt using namespace std int
main() int i 10 cout ltlt i ltlt "\n" cout
ltlt i ltlt "\n" return 0

• The statement int i 10 is used to define one
  variable named i with type of integer and value
  is 10

4
Introduction to Pointer
include ltiostreamgt using namespace std int
main() int i 10 cout ltlt i ltlt "\n" cout
ltlt i ltlt "\n" return 0

• At this point we might agree that there are only
  two entities exist with that single statement
  which are i and its value 10

5
Introduction to Pointer
include ltiostreamgt using namespace std int
main() int i 10 cout ltlt i ltlt "\n" cout
ltlt i ltlt "\n" return 0

• Below is the possible output of the program10
• 0xfeed4d84

6
Introduction to Pointer
include ltiostreamgt using namespace std int
main() int i 10 cout ltlt i ltlt "\n" cout
ltlt i ltlt "\n" return 0

• From the output we know that there are other
  entity which is 0xfeed4d84

7
Introduction to Pointer
include ltiostreamgt using namespace std int
main() int i 10 cout ltlt i ltlt "\n" cout
ltlt i ltlt "\n" return 0

• Right now we should know that there are three
  entities exist with that single statement which
  are i, 10 and 0xfeed4d84

8
Introduction to Pointer

• To better understand this situation we could try
  to imagine that the computer main memory (RAM)
  may could be represented as a table below

Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfeed4d84 10
. . . . . . . . . . . .
. . . . . . . . . . . .
. . . . . . . . . . . .
9
Introduction to Pointer

• Each time variable is defined it will be set by
  the system to refer to some address in the
  computer main memory

Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfeed4d84 10
. . . . . . . . . . . .
. . . . . . . . . . . .
. . . . . . . . . . . .
10
Introduction to Pointer

• We can conclude that variable i is used to refer
  to the address 0xfeed4d84 in the main memory
  which store the value of integer 10

Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfeed4d84 10
. . . . . . . . . . . .
. . . . . . . . . . . .
. . . . . . . . . . . .
11
Introduction to Pointer

• This is the nature for most of programming
  languages where its easy to get back the value
  of 10 from the memory by remembering i instead
  of 0xfeed4d84

Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfeed4d84 10
. . . . . . . . . . . .
. . . . . . . . . . . .
. . . . . . . . . . . .
12
Introduction to Pointer

• Base on our new level of understanding we might
  want to refine the previous simple C code as
  below

include ltiostreamgt using namespace std int
main() int i 10 cout ltlt Value of i
ltlt i ltlt "\n" cout ltlt Address of i ltlt i
ltlt "\n" return 0
13
Introduction to Pointer

• Also note that i is a syntax if we want to get
  the address referred by the variable i and its
  also applied to other type of variables (char,
  float, double)

include ltiostreamgt using namespace std int
main() int i 10 cout ltlt Value of i
ltlt i ltlt "\n" cout ltlt Address of i ltlt i
ltlt "\n" return 0
14
Introduction to Pointer

• Before go further you should try to make your own
• conclusion by answering the following questions
  
• What are variable, address, value and memory?
• How to get the address of particular defined
  variables?

15
Introduction to Pointer

• Base on the C code below we know that we can
  print out the address of i

include ltiostreamgt using namespace std int
main() int i 10 cout ltlt Value of i
ltlt i ltlt "\n" cout ltlt Address of i ltlt i
ltlt "\n" return 0
16
Introduction to Pointer

• Can we store the address of i into other
  variable?

include ltiostreamgt using namespace std int
main() int i 10 cout ltlt Value of i
ltlt i ltlt "\n" cout ltlt Address of i ltlt i
ltlt "\n" return 0
17
Introduction to Pointer

• You could try by adding a few lines of code
  below.

include ltiostreamgt using namespace std int
main() int i 10 cout ltlt Value of i
ltlt i ltlt "\n" cout ltlt Address of i ltlt i
ltlt "\n" int p p i return 0
18
Introduction to Pointer

• At the compilation time (linux) you might get the
  errorerror invalid conversion from int to int
  

include ltiostreamgt using namespace std int
main() int i 10 cout ltlt Value of i
ltlt i ltlt "\n" cout ltlt Address of i ltlt i
ltlt "\n" int p p i return 0
19
Introduction to Pointer

• It is due to the fact that variable p is declared
  to store the value of integer and not the address
  of memory that store integer value

include ltiostreamgt using namespace std int
main() int i 10 cout ltlt Value of i
ltlt i ltlt "\n" cout ltlt Address of i ltlt i
ltlt "\n" int p p i return 0
20
Introduction to Pointer

• To declare p so it can store the address of
  memory that store integer value just change the
  statement from int p to int p

include ltiostreamgt using namespace std int
main() int i 10 cout ltlt Value of i
ltlt i ltlt "\n" cout ltlt Address of i ltlt i
ltlt "\n" int p p i return 0
21
Introduction to Pointer

• To declare p so it can store the address of
  memory that store integer value just change the
  statement from int p to int p

include ltiostreamgt using namespace std int
main() int i 10 cout ltlt Value of i
ltlt i ltlt "\n" cout ltlt Address of i ltlt i
ltlt "\n" int p p i return 0
22
Introduction to Pointer

• Print out the information for p by using the
  pattern we print out the information for i

include ltiostreamgt using namespace std int
main() int i 10 cout ltlt Value of i
ltlt i ltlt "\n" cout ltlt Address of i ltlt i
ltlt "\n" int p p i return 0
23
Introduction to Pointer

• Try print out the information of p by using the
  pattern we print out the information of i

include ltiostreamgt using namespace std int
main() int i 10 cout ltlt Value of i
ltlt i ltlt "\n" cout ltlt Address of i ltlt i
ltlt "\n" int p p i cout ltlt Value
of p ltlt p ltlt "\n" cout ltlt Address of p
ltlt p ltlt "\n" return 0
24
Introduction to Pointer

• The possible output may look like below

Value of i 10 Address of i 0xbfe35f9c
Value of p 0xbfe35f9c Address of p 0xbfe35f98
25
Introduction to Pointer

• Notice that Address of i and Value of p got the
  same number which is 0xbfe35f9c

Value of i 10 Address of i 0xbfe35f9c
Value of p 0xbfe35f9c Address of p 0xbfe35f98
26
Introduction to Pointer

• To get a better understanding, create a table
  that representing the current state of main
  memory for this situation

Value of i 10 Address of i 0xbfe35f9c
Value of p 0xbfe35f9c Address of p 0xbfe35f98
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 10
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
27
Introduction to Pointer

• i is an integer and p is a pointer that store the
  address referred by i

Value of i 10 Address of i 0xbfe35f9c
Value of p 0xbfe35f9c Address of p 0xbfe35f98
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 10
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
28
Introduction to Pointer

• Its possible to access the value of i via p

cout ltlt Value of i via p is ltlt p ltlt
"\n"
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 10
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
29
Introduction to Pointer

• This is what we call pointer dereferencing as it
  will refer to the address stored by the pointer

cout ltlt Value of i via p is ltlt p ltlt
"\n"
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 10
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
30
Introduction to Pointer

• This is what we call pointer dereferencing as it
  will refer to the address stored by the pointer

cout ltlt Value of i via p is ltlt p ltlt
"\n"
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 10
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
31
Introduction to Pointer

• Its also possible to change the value of i by
  dereferencing p

p 20 cout ltlt Value of i after p
20 is ltlt i ltlt "\n"
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 10
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
32
Introduction to Pointer

• Its also possible to change the value of i by
  dereferencing p

p 20 cout ltlt Value of i after p
20 is ltlt i ltlt "\n"
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 10
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
33
Introduction to Pointer

• Its also possible to change the value of i by
  dereferencing p

p 20 stdcout ltlt Value of i after
p 20 is ltlt i ltlt "\n"
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 10
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
34
Introduction to Pointer

• Its also possible to change the value of i by
  dereferencing p

p 20 stdcout ltlt Value of i after
p 20 is ltlt i ltlt "\n"
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
35
Introduction to Pointer

• Its also possible to change the value of i by
  dereferencing p

p 20 stdcout ltlt Value of i after
p 20 is ltlt i ltlt "\n"
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
36
Introduction to Pointer

• The program that we should have so far to
  understand the pointer

include ltiostreamgt using namespace std int
main() int i 10 cout ltlt Value of i
ltlt i ltlt "\n" cout ltlt Address of i ltlt i
ltlt "\n" int p p i cout ltlt Value
of p ltlt p ltlt "\n"cout ltlt Address of p
ltlt p ltlt "\n" cout ltlt Value of i via p is
ltlt p ltlt "\n" p 20 cout ltlt Value
of i after p 20 is ltlt i ltlt
"\n" return 0
37
Introduction to Pointer

• Notice that after i and p are defined they are
  called with different approaches/manners which
  are i, i, p, p, and p

include ltiostreamgt using namespace std int
main() int i 10 cout ltlt Value of i
ltlt i ltlt "\n" cout ltlt Address of i ltlt i
ltlt "\n" int p p i cout ltlt Value
of p ltlt p ltlt "\n"cout ltlt Address of p
ltlt p ltlt "\n" stdcout ltlt Value of i via
p is ltlt p ltlt "\n" p 20 stdcout ltlt
Value of i after p 20 is ltlt i ltlt
"\n" return 0
38
Introduction to Pointer

• Using the table of memory below we can visualize
  what i, i, p, p, and p are all about

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
39
Introduction to Pointer

• There is no i as i is not a pointer

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
40
Introduction to Pointer

• The pointer p can also be assigned with the
  memory address allocated without using any
  defined and named variable such as i

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
41
Introduction to Pointer

• This technique referred as a dynamic memory
  allocation and can be applied as follows

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
42
Introduction to Pointer

• This technique referred as a dynamic memory
  allocation and can be applied as followsp
  new int

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
43
Introduction to Pointer

• This technique referred as a dynamic memory
  allocation and can be applied as followsp
  new int

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f9c
. . . . . . . . . . . .
. . . . . . . . . . . .
44
Introduction to Pointer

• This technique referred as a dynamic memory
  allocation and can be applied as followsp
  new int

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f9c
??? int 0xbfe35f?? ???
. . . . . . . . . . . .
45
Introduction to Pointer

• This technique referred as a dynamic memory
  allocation and can be applied as followsp
  new int

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f9c
??? int 0xbfe35f?? ???
. . . . . . . . . . . .
46
Introduction to Pointer

• This technique referred as a dynamic memory
  allocation and can be applied as followsp
  new int

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f9c
??? int 0xbfe35f?? ???
. . . . . . . . . . . .
47
Introduction to Pointer

• This technique referred as a dynamic memory
  allocation and can be applied as followsp
  new int

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f9c
??? int 0xbfe35f?? ???
. . . . . . . . . . . .
48
Introduction to Pointer

• This technique referred as a dynamic memory
  allocation and can be applied as followsp
  new int

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f??
??? int 0xbfe35f?? ???
. . . . . . . . . . . .
49
Introduction to Pointer

• This technique referred as a dynamic memory
  allocation and can be applied as followsp
  new int

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f??
??? int 0xbfe35f?? ???
. . . . . . . . . . . .
50
Introduction to Pointer

• This technique referred as a dynamic memory
  allocation and can be applied as followsp
  new int

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f??
??? int 0xbfe35f?? ???
. . . . . . . . . . . .
51
Introduction to Pointer

• This technique referred as a dynamic memory
  allocation and can be applied as followsp
  new intp 30

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f??
??? int 0xbfe35f?? ???
. . . . . . . . . . . .
52
Introduction to Pointer

• This technique referred as a dynamic memory
  allocation and can be applied as followsp
  new intp 30

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f??
??? int 0xbfe35f?? ???
. . . . . . . . . . . .
53
Introduction to Pointer

• This technique referred as a dynamic memory
  allocation and can be applied as followsp
  new intp 30

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f??
??? int 0xbfe35f?? 30
. . . . . . . . . . . .
54
Introduction to Pointer

• This technique referred as a dynamic memory
  allocation and can be applied as followsp
  new intp 30

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f??
??? int 0xbfe35f?? 30
. . . . . . . . . . . .
55
Introduction to Pointer

• Beware that the address 0xbfe35f?? is allocated
  using dynamic memory allocation so it doesnt
  have any defined variable referring to it
  (variable name assign with ???)

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f??
??? int 0xbfe35f?? 30
. . . . . . . . . . . .
56
Introduction to Pointer

• If the program stop right now, the operating
  system aware and able to release/freeing the
  memory space at 0xbfe35f9c and 0xbfe35f98 as it
  was formally defined and named with i and p

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f??
??? int 0xbfe35f?? 30
. . . . . . . . . . . .
57
Introduction to Pointer

• Its not the same for 0xbfe35f?? as it was
  allocated using dynamic memory allocation and
  require the programmer manually release/freeing
  it

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f??
??? int 0xbfe35f?? 30
. . . . . . . . . . . .
58
Introduction to Pointer

• It can be done by using delete function and set p
  to NULL as below each time before the program
  exit

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f??
??? int 0xbfe35f?? 30
. . . . . . . . . . . .
59
Introduction to Pointer

• It can be done by using delete function and set p
  to NULL as below each time before the program
  exit delete p

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f??
??? int 0xbfe35f?? 30
. . . . . . . . . . . .
60
Introduction to Pointer

• It can be done by using delete function and set p
  to NULL as below each time before the program
  exitdelete p

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f??
. . . int 0xbfe35f?? 0
. . . . . . . . . . . .
61
Introduction to Pointer

• It can be done by using delete function and set p
  to NULL as below each time before the program
  exit delete pp NULL

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 0xbfe35f??
. . . int 0xbfe35f?? 0
. . . . . . . . . . . .
62
Introduction to Pointer

• It can be done by using delete function and set p
  to NULL as below each time before the program
  exitdelete pp NULL

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c 20
p int 0xbfe35f98 NULL
. . . int 0xbfe35f?? 0
. . . . . . . . . . . .
63
Introduction to Pointer

• Is the current situation below is valid or
  allowed?

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c ???
p int 0xbfe35f98 0xbfe35f??
f float 0xbfe35f?? ???
. . . . . . . . . . . .
64
Introduction to Pointer

• It is not valid or allowed as p is defined to
  only hold the address of integer while 0xbfe35f??
  is the address of float

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c ???
p int 0xbfe35f98 0xbfe35f??
f float 0xbfe35f?? ???
. . . . . . . . . . . .
65
Introduction to Pointer

• This situation can be experimented by adding the
  following lines of code and will get an error at
  compilation timefloat f 1.7p f

p
p
i
p
i
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xbfe35f9c ???
p int 0xbfe35f98 0xbfe35f??
f float 0xbfe35f?? ???
. . . . . . . . . . . .
66
Introduction to Pointer

• In certain circumstances it also possible to have
  two pointer that point to the same address as
  below

p
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfe35f9c 20
p int 0xbfe35f98 0xfe35f9c
. . . . . . . . . . . .
67
Introduction to Pointer

• In certain circumstances it also possible to have
  two pointer that point to the same address as
  belowint p2

p
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfe35f9c 20
p int 0xbfe35f98 0xfe35f9c
. . . . . . . . . . . .
68
Introduction to Pointer

• In certain circumstances it also possible to have
  two pointer that point to the same address as
  belowint p2

p
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfe35f9c 20
p int 0xbfe35f98 0xfe35f9c
p2 int 0xbfe35f?? . . .
69
Introduction to Pointer

• In certain circumstances it also possible to have
  two pointer that point to the same address as
  belowint p2 p2 p

p
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfe35f9c 20
p int 0xbfe35f98 0xfe35f9c
p2 int 0xbfe35f?? . . .
70
Introduction to Pointer

• In certain circumstances it also possible to have
  two pointer that point to the same address as
  belowint p2 p2 p

p
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfe35f9c 20
p int 0xbfe35f98 0xfe35f9c
p2 int 0xbfe35f?? 0xfe35f9c
71
Introduction to Pointer

• In certain circumstances it also possible to have
  two pointer that point to the same address as
  belowint p2 p2 p

p
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfe35f9c 20
p int 0xbfe35f98 0xfe35f9c
p2 int 0xbfe35f?? 0xfe35f9c
p2
72
Introduction to Pointer

• Using the memory of table like below might help
  us to better understand the pointer but its not
  practical for complex data type such as class

p
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfe35f9c 20
p int 0xbfe35f98 0xfe35f9c
. . . . . . . . . . . .
73
Introduction to Pointer

• We can simplify it as follows

p
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfe35f9c 20
p int 0xbfe35f98 0xfe35f9c
. . . . . . . . . . . .
74
Introduction to Pointer

• We can simplify it as follows

p
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfe35f9c 20
p int 0xbfe35f98 0xfe35f9c
. . . . . . . . . . . .
75
Introduction to Pointer

• We can simplify it as follows

p
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfe35f9c 20
p int 0xbfe35f98 0xfe35f9c
. . . . . . . . . . . .
i
20
76
Introduction to Pointer

• We can simplify it as follows

p
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfe35f9c 20
p int 0xbfe35f98 0xfe35f9c
. . . . . . . . . . . .
i
20
77
Introduction to Pointer

• We can simplify it as follows

p
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfe35f9c 20
p int 0xbfe35f98 0xfe35f9c
. . . . . . . . . . . .
i
20
p
.
78
Introduction to Pointer

• We can simplify it as follows

p
Variable Name Type Address Value
. . . . . . . . . . . .
i int 0xfe35f9c 20
p int 0xbfe35f98 0xfe35f9c
. . . . . . . . . . . .
i
20
p
.
79
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

80
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

81
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
p2
.
temp
.
82
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
p2
.
temp
.
83
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
temp
.
84
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
temp
.
85
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
temp
.
86
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
temp
.
87
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
temp
.
88
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
???
temp
.
89
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
???
temp
.
90
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
???
temp
.
91
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
???
temp
.
92
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
???
temp
.
93
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
???
temp
.
94
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
???
temp
.
95
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
???
temp
.
96
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
30
temp
.
97
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
30
temp
.
98
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
30
temp
.
99
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
30
temp
.
100
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
30
temp
.
101
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
30
temp
.
102
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
30
temp
.
103
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
30
temp
.
104
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
30
temp
.
105
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
30
temp
.
106
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
30
temp
.
107
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
30
temp
.
108
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temp temp NULL

p
.
i
10
p2
.
???
30
temp
.
109
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temptemp NULL

p
.
i
10
p2
.
???
30
temp
.
110
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temptemp NULL

p
.
i
10
p2
.
???
30
temp
.
111
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temptemp NULL

p
.
i
10
p2
.
???
30
temp
.
112
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temptemp NULL

p
.
i
10
p2
.
???
30
temp
.
113
Introduction to Pointer

• Now you should able to understand basic pointer
  operations below by using the simplified version
  of pointer representation technique explained in
  the previous slide int p, p2, temp int
  i 10 p ip2 new intp2 30temp
  pp p2p2 temptemp NULL

p
.
i
10
p2
.
???
30
temp
.
114
Conclusion

• Each time we declare variable there are three
  main entities exist which are the variable name,
  its value, and address in memory referred by the
  variable
• We can get the address of variables by using the
  syntax var_name
• There is special variable which is called as
  pointer that can store/hold address referred by
  other variables
• For variable of type pointer declare as T P, P
  can only store address referred by other
  variables with type T
• Dereferencing is the term used to access the
  value of other variable point by the pointer