1.2.4 types of programming language

Question 1

what is a computer program

Answer 1

• series of statements (instructions) that are executed one after another

Question 2

all but the most trivial (insignificant) of programs tend to do what 3 things

Answer 2

• accept input
• process data
• produce output

Question 3

what are the 3 programming constructs (used in procedural languages)

Answer 3

• sequence
• selection
• iteration

Question 4

what is sequencing

Answer 4

• executing instructions one after another

Question 5

what is selection

Answer 5

• allows a program to branch and follow a different direction depending on outcome of a certain condition

Question 6

what is iteration

Answer 6

• repeating / looping sections of code

Question 7

how do you create an infinite loop

Answer 7

WHILE True

Question 8

what is a FOR loop (type and what does it mean)

Answer 8

• count-controlled loop
• used when required number of iterations is known ahead of execution

Question 9

what is a WHILE loop (type and what does it mean)

Answer 9

• condition-controlled loop
• used when required number of iterations isn’t known because the variable used to determine when the iteration ends is changing within the iteration itself

Question 10

what is a DO… UNTIL loop

Answer 10

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

Question 11

what is the difference between WHILE loop and DO…UNTIL loop

Answer 11

• WHILE loop, condition checked at start (if condition met, we may never execute the following lines of code in WHILE loop)
• DO… UNTIL loop always executes code once before checking exit condition at end

Question 12

what do programming constructs do

Answer 12

• control flow of program

Question 13

What is program flow?

Answer 13

The path that a program follows as it runs from start to finish.

Question 14

what is nesting

Answer 14

• process of putting one statement inside another
• this can be achieved through both iteration and selection statements

Question 15

What is a variable?

Answer 15

• pointer to a memory location that holds a value. It is defined by a name/label.

CAN BE CHANGED WHILE THE PROGRAM IS RUNNING.

Question 16

What is a constant?

Answer 16

• a memory location that holds a value. It is defined by a name/label

CANNOT BE CHANGED WHILE THE PROGRAM IS RUNNING

Question 17

what is a subroutine

Answer 17

• block of code given a unique, identifiable name within a program

Question 18

why do we use subroutines

Answer 18

• break down larger problem into series of smaller + more manageable problems
• this makes code easier to write, debug and test
• creates reusable components

Question 19

What is a similarity and a difference between a procedure and a function?

Answer 19

• Both are blocks of code (provide structure to code) which carry out a set task
• they are defined under a name which can be called and run simply by stating name of the function / procedure.
• Functions return values whereas procedures only execute commands.
• functions also create reusable program components

Question 20

what are procedures and functions similar to in OOP

Answer 20

• methods

Question 21

what is casting

Answer 21

• converting value into a different data type
• e.g string to integer using command int

Question 22

Give examples of arithmetic operators.

Answer 22

+ (addition)
- (subtraction)
* (multiplication)
/ (division)
^ or ** (exponentiation)
MOD or % (remainder)
DIV or // (e.g 7 DIV 2 = 3, its the nearest integer answer)

Question 23

Give examples of comparison operators.

Answer 23

== (equal to)
!= (not equal to)
< (less than)
<= (less than or equal to)
> (greater than)
>= (greater than or equal to)

Question 24

Give examples of boolean operators.

Answer 24

AND / OR / NOT / XOR

Question 25

what do boolean expressions always equate to

Answer 25

• True or False

Question 26

What does an assignment operator do?

Answer 26

• assigns / supplies a value to a variable or constant
• performed with the = symbol

Question 27

What does a compound assignment operator do?

Answer 27

• assigns a value to a variable while also carrying out an arithmetic operation.

Question 28

what is string manipulation

Answer 28

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

Question 29

give some string manipulation commands

Answer 29

• .length
• .substring
• .upper (returns original string in upper case)
• .lower (returns original string in lower case)
• .isupper (returns true if all characters in upper case)
• .islower (returns true if all characters in lower case)

Question 30

what are the 2 string manipulations commands for ASCII

Answer 30

• ascii = ord(“A”) which returns 65 which is the ASCII value of character
• char = chr(65) which returns A which is the character from ASCII value

Question 31

What is string handling? (Give examples)

Answer 31

• a set of commands which can carry out useful operations on a string data type.
  e.g. search, copy, compare, concatenate

Question 32

What is file handling?

Answer 32

A set of procedures that allow a program to create, read from and write to, open and close files that are saved in storage and not in memory.

Question 33

in summary, how do you write to a file

Answer 33

• open file for creating/overwriting or appending
• write data to file
• close file

Question 34

in summary, how do you read/search data from a file

Answer 34

• open file for reading data
• assign Boolean variable to false to indicate end of file not reached
• while end of file is false and search item not found: read data from file and if data matches what’s being searched for, assign data to variable or output. Then check if end of file has been reached and assign Boolean variable to be true
• when end of file is true and search item found, close file