Programming

Question 1

What is an algorithm?

Answer 1

An algorithm is a sequence of instructions that can be followed to solve a problem, and that always terminates.

Question 2

How is pseudocode used?

Answer 2

Pseudocode is used to write instructions using statements that are somewhere between English and a programming language.
There are guidelines for writing pseudocode, but no strict rules.
Pseudocode is an aid to work out the steps needed to solve a problem before beginning to code.

Question 3

How are flowcharts used?

Answer 3

A flowchart is a diagram used to illustrate the steps of an algorithm.
Flowcharts are made up of symbols, each containing a single step of the algorithm.
The shape of the symbol represents the type of process that the symbol contains.
Arrows are used to show the flow of execution, meaning that flowcharts can represent all the core concepts of programming, namely sequence, selection, and iteration.

Question 4

What is a variable?

Answer 4

A named piece of memory that holds a value. The value it holds can, and often does, change during the running of a program.

Question 5

What is a constant?

Answer 5

A named piece of memory where the value cannot be changed while a program runs.

Question 6

Why are constants useful?

Answer 6

Constants are useful because they are declared and assigned once, but can be referred to over and over again throughout the program. This means that if the programmer needs to change the value throughout the program code, they only need to make one change. This can help make a program easier to maintain.

Question 7

What naming conventions do constants follow?

Answer 7

Constants follow the same naming conventions as variables, except that they are often written in uppercase. Some programming languages, such as Python, do not support constants.

Question 8

What is a data type?

Answer 8

How data is stored depends on what the data is. A data type is defined by the values it can take or the operations which can be performed on it.

Question 9

How do programmers decide which data type to use?

Answer 9

In some situations, it might be possible to store one piece of data using various different data types. In this case, the programmer must decide which option is the best suited to solving a particular problem or which is the most memory-efficient.
For example, if a programmer needs to store a user’s age in years, they could use a string or an integer. In this situation, using an integer would be the best option, because a person’s age is only ever going to contain numerical digits.

Question 10

What is an integer?

Answer 10

A whole number, which can be positive, negative, or zero.

Question 11

What is a real/float?

Answer 11

A number which can have a decimal part. The number can be positive, negative, or zero.

Question 12

What is a Boolean?

Answer 12

A value that is either True or False.

Question 13

What is a character?

Answer 13

A single number, letter, or symbol, enclosed in quotation marks, e.g. ‘a’, ‘9’, ‘@’, ‘!’.

Question 14

What is a string?

Answer 14

A list of characters enclosed in quotation marks, e.g. ‘Hello’, ‘ABC123!’.

Question 15

What is a date/time?

Answer 15

A way of storing a point in time. Many different formats are used.

Question 16

What is a pointer/reference?

Answer 16

A way of storing memory addresses.

Question 17

What is a record?

Answer 17

A collection of fields, each of which could have a different data type. You can think of a record as a row from a table.

Question 18

What is an array?

Answer 18

A finite, indexed set of related elements each of which
has the same data type.

Question 19

What is a list (Python)?

Answer 19

A list is similar to an array, but more flexible. It can be altered while the program is running, doesn’t have a fixed length, and elements can be of different data types.

Question 20

What are assignment statements written with in pseudocode?

Answer 20

Assignment statements can be written using <– or =.
E.g. Name <– “David”

Question 21

Which symbol is used for addition in Python?

Answer 21

+

Question 22

Which symbol is used for subtraction in Python?

Answer 22

-

Question 23

Which symbol is used for multiplication in Python?

Answer 23

*

Question 24

Which symbol is used for division in Python?

Answer 24

/

Question 25

What symbol is used for exponentials in Python?

Answer 25

**
e.g. 3**2 = 9

Question 26

What is integer division/DIV?

Answer 26

It returns the integer part of a division.
E.g. 5 DIV 2 = 2

Question 27

Which symbol is used to represent integer division in Python?

Answer 27

//
E.g. 5//2 = 2

Question 28

What is the modulo function/MOD?

Answer 28

It returns the remainder of a division.
E.g. 5 MOD 2 = 1

Question 29

Which symbol is used to represent the modulo function in Python?

Answer 29

%
E.g. 5%2 = 1

Question 30

What are user-defined data types and why are they used?

Answer 30

User-defined data types are derived from existing data types to create a customised data structure. Creating and using user-defined data types allows a programmer to ensure that a solution is as memory efficient as possible.
For example, a shop might use a user-defined data type called Customer to store information about their customers. The user-defined data type might have attributes like Forename, Surname and EmailAddress.

Question 31

What is variable/constant declaration?

Answer 31

Creating a variable or constant for the first time, giving it a name
and sometimes a data type. This allocates a portion of
the computer’s memory to the variable/constant.
(In Python, variables and constants don’t need to be declared before assignment)

Question 32

What is assignment?

Answer 32

Assigning a value to a variable or a constant.

Question 33

What is iteration?

Answer 33

Repeating an instruction, this could be definite or
indefinite.

Question 34

What is selection?

Answer 34

When different sections of code are executed based on whether a condition is met or not.

Question 35

What is a subroutine?

Answer 35

A named block of code containing a set of instructions.
Subroutines can be called from anywhere within a program and are typically designed to carry out a frequently used action.

Question 36

Which Python function can be used to find the length of a string?

Answer 36

len()

Question 37

How do you find the character at a specific position in a string?

Answer 37

In Python this works similarly to selecting an element from a list based on its index.
The syntax is like this: String[index]
E.g.
greeting = “Hello”
print(greeting[4]) prints o
Remember indexing starts at 0.

Question 38

How do you select a substring from a string?

Answer 38

Similar to getting a singular character, but you have to specify two values.
The syntax is like this: String[start index, end index + 1]
E.g.
greeting = “Hello there”
print(greeting[6,10]) prints “there”
Remember indexing starts at 0.

Question 39

What is concatenation?

Answer 39

Joining multiple string together.

Question 40

How do you concatenate strings in Python?

Answer 40

You can concatenate strings either using commas or plus signs.
E.g.
print(“Hello” , “there”)
print(“Hello” + “ there”)
Both print “Hello there”
Commas automatically add a space between the strings that are being concatenated.

Question 41

How do you concatenate a string and an integer or float in Python?

Answer 41

If using a plus sign, you have to convert the integer/float into a string.
price = 20
E.g. print(“This costs £” +str(price))
Prints “This costs £20”
Commas don’t require you to change the datatype, but do add a space between each item that you’re concatenating together.

Question 42

How do you find the ASCII code of a character in Python?

Answer 42

Using the built-in ord() function.
e.g. print(ord(“L”)) would print 76.

Question 43

How do you convert an ASCII code to its character value in Python?

Answer 43

Using the built-in chr() function.
e.g. print(chr(65)) prints “A”

Question 44

How do you convert a string to an integer in Python?

Answer 44

Using the built-in int() function.
e.g. int(“10”) converts the string “10” to the integer 10.

Question 45

How do you convert a string to a float in Python?

Answer 45

Using the built-in float() function.
e.g. float(“10.3”) converts the string “10.3” to the float 10.3.

Question 46

How do you convert an integer or a float to a string in Python?

Answer 46

Using the built-in str() function.
e.g. str(10) converts the integer 10 into the string “10”.

Question 47

How do you convert a date/time into a string in Python?

Answer 47

Using the built-in str() function.