2.2 Programing Techniques

Question 1

What’s a variable?

Answer 1

Variables can change the data value that is assigned to them while the program is running.
-lower case first letter

Question 2

What’s a constant?

Answer 2

A constant is an assigned data value at the design time of a program that can’t be changed. If you attempt to change the value of a constant in a program then the interpreter or compiler will return an error. It’s fixed for the duration of the program.
-CAPITALS for naming

Question 3

What can data values be stored as?

Answer 3

Constants or variables

Question 4

What’s the name of constant or variable linked to?

Answer 4

A memory location, that stores the data value. The size of the memory location depends on the data type.

Question 5

What are the five main data types for programming languages?

Answer 5

Integer
Real(or float)
Boolean
Character
String

Question 6

What’s a pseudocode representation, description and an example of an integer?

Answer 6

Pseudocode:INT
Description:Whole numbers only.
E.g: 0,928,-167

Question 7

What’s a pseudocode representation, description and an example of an real(or float)?

Answer 7

Pseudocode:REAL
Description:Numbers that have a decimal part
E.g: 0.15,-5.78,10.0

Question 8

What’s a pseudocode representation, description and an example of an Boolean?

Answer 8

Pseudocode: BOOL
Description: Can only take one of two values, usually TRUE or FALSE.
E.g: true/false, 1/0, yes/no

Question 9

What’s a pseudocode representation, description and an example of an character?

Answer 9

Pseudocode:CHAR
Description:A single letter, number or symbol
E.g: D, o, 7, ;, €

Question 10

What’s a pseudocode representation, description and an example of an string?

Answer 10

Pseudocode:STRING
Description:Used to represent text, it’s a collection of characters.
E.g: “€>ehruK3nj”

Question 11

What’s the assignment operator?

Answer 11

=
It’s used to assign values to constants or variables.
-the name of the constant or variable on the left hand side of the =
-whatever your assigning should be on the right of the =

Question 12

What do comparison operators do?

Answer 12

They compare the expression on the left hand side to the expression to their right hand side and produce a Boolean value.

Question 13

What’re 6 comparison operators and what do they mean?

Answer 13

== :equal to
<> or != :not equal to
< :less than
> :greater than
<= :less than or equal to
>= :greater than or equal to

Question 14

What’s casting?

Answer 14

Languages have functions that allow you to manually convert between data types this is know as casting. This can be done using the int(), float(), bool(), str() commands.

Question 15

What happens if you convert the integer 1 into a float?

Answer 15

It becomes 1.0

Question 16

What happens if you change the integer 1 into Boolean?

Answer 16

It’s converted into the Boolean value True

Question 17

What’s the exponential symbol, example and explanation?

Answer 17

Symbol:^ or **
Example: 2^3 =8
Explanation:it’s used to raise a number to a power

Question 18

What’s the quotient symbol, example and explanation?

Answer 18

Symbol: DIV
Example: 20 DIV 3 =6
Explanation:it returns the whole number part of a division

Question 19

What’s the remainder(modulus) symbol, example and explanation?

Answer 19

Symbol: MOD or %
Example: 20 MOD 3 =2
Explanation:it gives the remainder of the division

Question 20

How can you find the ascii number of characters and vice versa?

Answer 20

ASC() -converts a character into the corresponding ascii number
CHR() -converts the ASCII number into the equivalent character

Question 21

What are strings normally written inside?

Answer 21

Speech marks “ “

But sometimes single quotation marks are used ‘ ‘

Question 22

How can strings be joined together and what’s the word for it?

Answer 22

By using the + operator and it’s called concatenation

Question 23

What are characters in string numbered from?

Answer 23

They start from 0 and increment by 1 each time

Question 24

What’re 5 string manipulation functions?

Answer 24

x.upper
x.lower
x.length
x[i]
x.subString(a, b)

Question 25

What’s the operation and effect on x = “Hello” of x.upper?

Answer 25

Operation:changes all character in string x to upper case
Effect:HELLO

Question 26

What’s the operation and effect on x = “Hello” of x.lower?

Answer 26

Operation:changes all the characters in the string x to lower case
Effect:hello

Question 27

What’s the operation and effect on x = “Hello” of x.length?

Answer 27

Operation:returns the number of characters in string x
Effect:5

Question 28

What’s the operation and effect on x = “Hello” of x[i]?

Answer 28

Operation:extracts the chapter in position i from x
Effect: x[1] = “e”

Question 29

What’s the operation and effect on x = “Hello” of x.subString(a,b)?

Answer 29

Operation:extracts a string starting from position a with length b from string x
Effect:x.subString(3,2) = “lo”

Question 30

What’s a sequence program flow?

Answer 30

Where the program runs the steps in the order they’re written

Question 31

What’s selection program flow?

Answer 31

Selection allows different paths through the code depending on the outcome of a condition.
▶ IF – THEN – ELSE – END IF
▶ Nested Ifs
▶ CASE

Question 32

What’s iteration program flow?

Answer 32

When a process or sequence in a computer program is repeated, this is an iteration. In a computer program, a common form of iterations is a loop.
▶ FOR – NEXT (Count Controlled)
▶ WHILE – END WHILE (Condition Controlled)
▶ REPEAT – UNTIL / DO – WHILE (Condition Controlled)

Question 33

What’re nested if statements?

Answer 33

When you put one if statement inside another.

• Nested ifs allow you to check more conditions once you’ve established that the previous condition is true
• if-elif can also check multiple conditions but only if the previous condition was false

Question 34

What’re switch case statements?

Answer 34

They check the specific value of a variable not just checking wether it’s true or false
They’re used when you want a program to perform different actions for different values of the same variable
-switch-case statements have a similar structure to if-elseif structure but they can test different values of a variable the down side however they can only check the value of one variable whereas if-elseif can check if multiple conditions are true

Question 35

What’re for loops?

Answer 35

Count controlled loops

They repeat what’s inside of them for a set amount of times

Question 36

What’re repeat loops?

Answer 36

Controlled by conditions

• controlled by a condition at the end of the loop and keeps going until the condition is true
• runs the code inside at least once
• you get an infinite loop if the condition is never true

Question 37

What’re while loops?

Answer 37

Controlled by conditions

• controlled by a condition at the start of the loop
• keep going while the condition is true
• never runs the code inside if the condition is initially false
• get an infinite loop if the condition is always true

Question 38

What’re do while loops?

Answer 38

Condition controlled loop

• controlled by a condition at the end of the loop
• keeps going while the condition is true
• always runs the code inside at least once
• get an infinite loop if the condition is always true

Question 39

When using external files what’s the first thing you need to do?

Answer 39

Open the external file
This is done by using an open command and assigning it to a variable
E.g. newFile = openRead(“newfile.txt”) -this allows you to read data from it
newFile = openWrite(“newfile.txt”) -this allows you to write data from your program to the file

Question 40

How can you write lines of text to a file?

Answer 40

Variable_name.writeLine()

Question 41

What’s the last thing you must do after using an external file?

Answer 41

Variable_name.close()

Question 42

How do you read from an external file?

Answer 42

Variable_name.readLine()

Question 43

How can you tell a program to stop reading an external file when it’s reached the end?

Answer 43

Variable_name.endOfFile()

Question 44

What are the three basic programming constructs?

Answer 44

Sequence, selection, iteration