Pointers Presentation

Pointers

By Sarah Gates

Starter Task

•
Short Discussion:

–
Emison
–

Pointers

–
Glenn
–

Hexadecimal numbers

•
What do you remember about them?

•
What was the defining points you remember
from those sessions?

Learning Objectives

•
Know the 2 different types of data structure
(Dynamic and Static)

•
Know what a pointer is in Programming and
where they are used.

•
Identify different types of pointers, and
understand why these different types are
needed.



First things first…

•
Data structure

–
A collection of data stored in memory, plus a number of
operations included by the software to manipulate the
data structure (Definition found on Teach ICT website
http://www.teach
-
ict.com/as_as_computing/ocr/H447/F453/3_3_5/dat
a_structures/miniweb/pg2.htm
)

•
Different types of Data structure

–
Dynamic (Stack) Where memory is allocated at the point
of run time.

–
Static (List) memory is allocated at the time the
structure is compiled and is fixed.



Pointers

•
Sometimes called “references” (e.g. in Perl…)

•
A variable which “points” to a location in the
memory of a computer.

–
Usually points to an address (numbered location of a
place in the memory),

–
Used in almost all programming languages including C,
C++, Pascal, Perl, and BASIC.

•
Different types of pointers

–
Managed

–
Unmanaged function pointers

–
Stack


An example

Cont

•
Address locations given in Hexadecimal
numbers

–
int

*
hardware_address

= (
int

*)0x7FFF;

–
an example of a pointer initialising to a
hexidecimal

address.

•
http://www.youtube.com/watch?v=f
-
pJlnpkLp0

•
A fun little video about pointers and
pointees

Finally: taken from
http://xkcd.com/138/