2.2 Programming Fundamentals

Question 1

Define variable

Answer 1

A value stored in memory that can change while the program is running

Question 2

Define constant

Answer 2

A value that does not change while the program is running, and is assigned when the program is designed

Question 3

Define assignment

Answer 3

Giving a variable or constant a value

Question 4

Define casting

Answer 4

Converting a variable from one data type to another

Question 5

Define input

Answer 5

A value is read from an input device e.g. keyboard

Question 6

Define output

Answer 6

Data generated by the computer and displayed to the user

Question 7

Advantages of constants

Answer 7

1) make a program easier to read as they are declared and assigned at the top of the program
2) can be changed easily by the programmer in one place in a program
3) instead of changing every instance of a value throughout a program
4) so less chance of errors
5) compiler can optimise code
6) which makes a program run more quickly

Question 8

Why is casting needed?

Answer 8

Inputs from the keyboard are always characters (multiple characters are called strings). However, for calculations, the ALU must use numbers so the string is cast to a number.

Question 9

What is sequence?

Answer 9

Executing one instruction after another

Question 10

What is selection?

Answer 10

A program branching depending on a condition

Question 11

What is iteration?

Answer 11

Repeating sections of code

Question 12

When are FOR loops used?

Answer 12

Count-controlled loops. Used when the number of iterations needed is known ahead of the iteration executing.

Question 13

When are WHILE loops used?

Answer 13

Condition-controlled loops. Used when the number of iterations is not known because the variable used to determine when the iteration ends is changing within the iteration itself

Question 14

When are DO…UNTIL loops used?

Answer 14

An alternative to WHILE where the code executes at least once before the condition is checked

Question 15

Casting to an integer

Answer 15

int()

Question 16

Casting to a real/float

Answer 16

real()/float()

Question 17

Casting to boolean

Answer 17

bool()

Question 18

Casting to a string

Answer 18

str()

Question 19

Casting to ASCII

Answer 19

ASC(b)

Question 20

Casting to a character

Answer 20

CHR(98)

Question 21

Example of a FOR loop

Answer 21

for rolls in range():

Question 22

Example of a WHILE loop

Answer 22

while answer != “Computer”:
answer = input(“Pass: “)
endwhile

Question 23

Example of a DO…UNTIL loop

Answer 23

do
answer = input(“Pass: “)
until answer == “Computer”

Question 24

Example of NOT

Answer 24

end_of_file = False
while not end_of_file

Question 25

Example of AND

Answer 25

end_of_file = False found = False while not end_of_file and not found

Question 26

Example of OR

Answer 26

if x==2 or x==4 while choice <1 or choice <3

Question 27

Why is casting necessary?

Answer 27

Casting is necessary so that sub-problems receive data in a format they are expecting. Casting allows numbers to be manipulates as strings and inputs that are always strings to become numbers.

Question 28

Examples of casting

Answer 28

x = str(x) casts the variable x to a string x = int(x) casts the variable to an integer

Question 29

What are telephone numbers stored as?

Answer 29

Strings. If the telephone no. was stored as an integer, we would lose the leading 0. Telephone numbers are also often entered with other symbols which aren't integers e.g. (07548) 433-844

Question 30

string manipulation (python) - string length

Answer 30

length = len(string)

Question 31

string manipulation - uppercase

Answer 31

ustring = string.upper()

Question 32

string manipulation - lowercase

Answer 32

lstring = string.lower()

Question 33

string manipulation - substrings

Answer 33

chars = string[2:3]

Question 34

string manipulation - getting number from ascii

Answer 34

ascii = ord("A")

Question 35

string manipulation - getting character from ascii

Answer 35

char = chr("65")

Question 36

example someText = "Computer Science" print(len(someText)) print(someText[3:6].upper())

Answer 36

16 PUT

Question 37

What is string manipulation?

Answer 37

The act of manipulating, extracting, or changing the characters in a string variable

Question 38

What is concatenation?

Answer 38

When strings are joined to form new strings (often done with the + operator)

Question 39

file handling - opening a file (not python)

Answer 39

file = open("file.txt")

Question 40

file handling - creating a new file (not python)

Answer 40

newFile("myfile.txt")

Question 41

file handling - writing lines (not python)

Answer 41

winners.writeLine()

Question 42

file handling - reading lines (not python)

Answer 42

winners.readLine()

Question 43

file handling - stop reading/signify end of file (not python)

Answer 43

winners.endOfFile()

Question 44

file handling - closing a file (not python)

Answer 44

winners.close()

Question 45

file handling - opening a file to read (python)

Answer 45

f = open("files.txt", "r")

Question 46

file handling - opening a file to write to/append (python)

Answer 46

f = open("files.txt","a")

Question 47

file handling - opening a file to create a new file/overwrite contents (python)

Answer 47

f = open("files.txt","w")

Question 48

file handling - close file (python)

Answer 48

f.close()