T2A Programming Basics

Why do we have different data types?

So code is memory efficient, robust (hard to break) and predictable

What are integers + memory size

Whole numbers, 2 bytes

What are floats/real + memory size

Whole number with decimal part, 4 bytes

What is a character + memory size

A single ASCII character, 1 byte

What is a string + memory size

Zero or more characters - inside quote marks, 1 byte per character

What is a boolean + memory size

Values of True or False, just one bit put high level languages 1 byte

How to define constants in pseudocode

Shown in uppercase

Why use a constant instead of variable

Prevents value from being changed accidentally in code, whos programmer value should stay the same throughout the program

What does concatenating mean?

Joining together

What is casting?

Functions used to convert data types

Why is casting used?

Different data types are represented differently in binary

Function to convert data types - pseudo code

DATATYPE1_TO_DATATYPE2(datatype1), CHAR, CODE, STRING, INT

What does CHAR_TO_CODE('a') do?

Gives 97 - evaluates to the number using ASCII

What does len(string) do?

Gives length of the string

What does SUBSTRING(start/index1, end/index2, string) do?

Will output the part of the string which starts at index1 letter and ends with index2 letter

How to find the position of a character in a string? Pseudocode

POSITION(string, character)

How make a string uppercase - pseudocode?

UPPERCASE(string) or string.UPPER_CASE

Definition of sequence?

the statements are executed one by one in the order they are written in

Definition of selection?

The next statement is executed depending on whether the condition being tested is True or False

What are nested if statements?

If statements inside another if statement

What are AND, OR and NOT called?

Boolean expressions

What does AND do?

Returns true if both conditions are true

What does OR do?

Returns true if either of the conditions are true

What does NOT do?

Switches the expression from True to false and vice versa

How to generate random numbers - pseudocode?

Import random

RANDOM_INT(num1, num2)

Definition of iteration

Repetition of a section of code

When are for loops used?

When you want to execute the loop a specified number of times

What iteration are for loops?

Count controlled iteration

When are while loops used?

When you want to execute the loop while a certain condition is true

When is a condition tested in a while loop?

At the beginning of the loop

What type of iteration is a while loop?

A condition controlled loop

For loop pseudocode?

FOR...ENDFOR

While loop - pseudocode?

WHILE...ENDWHILE

When are conditions tested in a repeat until loop

At the end of the loop

Repeat until loop pseudocode?

REPEAT...UNTIL

Definition of array

A data structure that allows you to hold many items of data which is referenced by one identifier

Condition of an array?

All items of data in the array must be the same data type

Advantages of arrays?

You don't have to use lots of variables, can be used in linear search, can be used in bubble sort

Disadvantages of arrays

Have a fixed size, Inefficiency of inserting/deleting items, can be memory inefficient, has to be same data type

How to swap items in a list?

list[0], list[4] = list[4], list[0] (swaps item 0 with item 4)

How to add items to a list?

list.append(item you want to append)

How to define arrays in pseudocode?

array arrayName[number of elements in array at beginning]

INDENT arrayName

How to make a list of 5 ""

list = [""]*5

Definition of a record

a data structure consisting of a number of fields which can all be of different data types

What is a field?

A single item of data in a record

Defining a record called film - pseudocode

RECORD recordName

INDENT fieldName1: data type

INDENT fieldName2: data type

ENDRECORD

Definition of instantiation

New instances of a record structure being made for different things

Instantiation - pseudocode?

newRecord

Updating a record - pseudocode?

recordName.fieldName

What is a Two-dimensional array?

a list made up of lists/lists in a list

How are position of elements represented in two-dimensional arrays? in python

list[a][b] where a = which 1 dimensional array the element is in b = index of which element in 1D array

What does len(listName) do? listName is a 2D array

Finds number of lists in the two-dimensional array

What does len(listName[1]) do? listName is a 2D array

Used to find number of elements in the one dimensional array (highlighted by the index) in the two dimensional array

Which programming language does the index list[a,b] work in?

Python NumPy array