Exam prep

Question 1

What is a bit?

Answer 1

Smallest bit of information. It’s a zero or a one.

Question 2

What is a byte?

Answer 2

8 bits. Those 8 bits are contiguous

Question 3

What is a word?

Answer 3

A set of bits. most common being 8, 16, 32 and 64. You can pass a word to the cpu for processing.

Question 4

What is fragmentation?

Answer 4

Storage space used in an inefficient way

Question 5

What is a bus error?

Answer 5

When the memory is accessed by words but stored as bytes.

when your processor cannot even attempt the memory access requested

Question 6

What is main memory?

Answer 6

This is your random access memory. Very fast memory that the cpu uses to temporarily store data.

Question 7

What is secondary memory?

Answer 7

This is your HDD or SSD. Long term storage. A little slow. Keeps information even after computer is switched off.

Question 8

What are I/O units

Answer 8

Peripherals used by humans to interact with the computer. Ie keyboard, mouse ect

Question 9

What is cached memory?

Answer 9

memory that is stored on the cpu chip or very close by on the motherboard. Very fast.

Question 10

What is a stack overflow? What may cause it?

Answer 10

A stack overflow is a run-time software bug when a program attempts to use more space than is available on the run-time stack

Question 11

What is the order hierarchy of software?

Answer 11

from bottom to top : Code, Data, Heap, Stack.

Question 12

(Hierarchy) What is code?

Answer 12

Where the compiled code resides. Usually read only.

Question 13

(Hierarchy) What is Data?

Answer 13

Where variables that are accessible to everything (ie global variables) reside.

Question 14

(Hierarchy) What is the stack? which way does it grow ?

Answer 14

The stack grows down. When we run our programs, the grow down on the stack.

. The stack is an area that typically has a predetermined size
. An example of allocating a variable to the stack would be : int a = 5;

stores temporary variables created by a function. In stack, variables are declared, stored and initialized during runtime.

Stores activation records

It is a temporary storage memory. When the computing task is complete, the memory of the variable will be automatically erased. The stack section mostly contains methods, local variable, and reference variables.

Question 15

(Hierarchy) What is the heap? Which way does it grow?

Answer 15

The heap grows up. When we dynamically allocate data this will grow up in the heap.

. The heap is also predetermined but can grow.
. the new keyword is used to allocate something to the heap.

int *hval = new int; This is dynamically allocating a pointer onto the heap that points to a
int.
*hval = 5; To give it a value you need to dereference the pointer.

Question 16

how many bytes is an int?

Answer 16

4 bytes

Question 17

Declare an int variable a on the stack equal to 5.

Answer 17

int a = 5;

Question 18

declare an int variable b on the heap qual to 5.

Answer 18

int* b = new int;

*b = 5;

Question 19

Declare a int array on the stack of size 5

Answer 19

int a[5];

Question 20

Declare a int array on the heap of size 5

Answer 20

int *b = new int[5];

Question 21

Vector3 is a structure within the program. How would you initialise it to the stack?

Answer 21

Vector3 vector;

Question 22

Vector3 is a structure within the program. How would you initialise it to the heap?

Answer 22

Vector3* vector = new Vector3;

Question 23

If you have an int a = new int; and int b = new int[5] on the heap, how would you delete them

Answer 23

delete a;

delete[] b;

Question 24

Are the contents of a pointer checked at compile time or runtime?

Answer 24

The contents of the pointer are checked in runtime. This is due to the fact that you can’t store a constant in a pointer.

Question 25

Convert 163 into binary

Answer 25

10100011

Question 26

convert 100101110 into decimal

Answer 26

302

Question 27

What is 2’s complement? what is the most negative number that can be represented in one byte?

Answer 27

-127

Question 28

What is the difference between an object and methods?

Answer 28

A method is a function that an object is able to use.

Question 29

What is Inheritance?

Answer 29

The capability of a class to derive properties and characteristics from another class is called Inheritance

Question 30

What is encapsulation?

Answer 30

Encapsulation is an Object Oriented Programming concept that binds together the data and functions that manipulate the data, and that keeps both safe from outside interference and misuse. … All variables or functions defined after the public specifier are accessible by all other functions in your program.

Question 31

What is polymorphism?

Answer 31

Polymorphism is the ability to create a property, a function or an object that has more than one realisation.

This is sometimes done by using the virtual keyword.

Question 32

What is slicing?

Answer 32

“Slicing” is where you assign an object of a derived class to an instance of a base class, thereby losing part of the information - some of it is “sliced” away.

For example,

class A {
   int foo;
};

class B : public A {
   int bar;
};
So an object of type B has two data members, foo and bar.

Then if you were to write this:

B b;

A a = b;
Then the information in b about member bar is lost in a.

Question 33

What is the memory hierarchical memory structure?

Answer 33

1) register memory
2) Cache memory
3) Main memory - ie ram
4) Secondary memory - ie ssd

Question 34

What are the five big O notation from least complex to most complex

Answer 34

1: O(1)
2: O(log n)
3: O(n)
4: O(n log n)
5: O(n*n)

Question 35

What is Coupling

Talk about loose coupling and high coupling

Answer 35

Coupling is the degree of dependance between two classes

Loose coupling means that the classes that are grouped have few interdependencies allowing you to change something without need to change a whole bunch of other code in connected classes

Tight or high coupling means that the classes have many interdependencies meaning that if you change something from one class, you’re going to have to change a lot of code that is connected to that class

Question 36

What is abstraction

Answer 36

methodology in which details of the programming codes are hidden away from the user, and only the essential things are displayed to the user.

Question 37

What is polymorphism

Answer 37

A oop concept that allows programmers to create functions and methods that can be implemented differently in child classes.

An example that we have used in this class is using the virtual keyword.

Question 38

What is cohesion

What is high cohesion?

What is low cohesion?

Answer 38

Cohesion refers to what the class (or module) can do. Low cohesion would mean that the class does a great variety of actions - it is broad, unfocused on what it should do. High cohesion means that the class is focused on what it should be doing, i.e. only methods relating to the intention of the class.

Question 39

What is method movement?

This applies to refactoring code.

Answer 39

Moving a method around in the class when refactoring code.

Question 40

What is a ‘has a’ relationship?

Answer 40

A has a relationship is a composition relationship.

ie, cart has meerkats

Question 41

What is a ‘is a’ relationship?

Answer 41

A is a relationship is an inheritance relationship.

ie, a piano is an instrument.

Question 42

What is the register’s memory used for?

Answer 42

Registers, on the other hand, are accessed as part of the machine’s computing instructions. When the machine processes “add x to y and store in z” it accesses registers*.

Question 43

What is the cache’s memory used for?

Answer 43

Caches live on the memory side of that. Loads and stores will treat cache just as they treat memory (only faster). Caches are addressed using memory addresses. And as far as the compute side knows, they’re accessing memory.

Question 44

Convert 126 into binary

Answer 44

1111110

Question 45

Convert 0xFE into decimal

Answer 45

-

Question 46

What is an objects state and behaviour?

Answer 46

state and behaviour are the basic properties of an Object.

state tells us about the type or the value of that object where as behaviour tells us about the operations or things that the object can perform.

For example let’s say we have an Object called car

so car object will have colour, engine type, wheels etc as it’s state,

this car object can run at 180kmph, it can turn right and left, it can go back and forth, it can carry 4 people etc. These are it’s behaviours.