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2.1.1: be able to write programs in a high-level programming language
Keyword
Definition
High level
a way of describing a programming language that hides some details of what the CPU and memory will do in order to make solving complex problems easier
Low level
a way of describing a programming language that gives you complete control over the CPU and memory in order to get maximum speed and efficiency
Program
the implementation of an algorithm in code
2.1.2: understand the benefit of producing programs that are easy to read and be able to use techniques (comments, descriptive names (variables, constants, subprograms), indentation) to improve readability and to explain how the code works
Keyword
Definition
Comments
sections of code that aren't executed but that describe how the rest of the code works
Constant
a value with a name, that is set once, before the program runs. It can be used multiple times but it's value never changes
Descriptive names
identifiers for variables, constants and subprograms that describe what they store or do
Indentation
using tabs and spaces to the left of a line of code to help show where it fits within the the structure of a program
Subprogram
a procedure or function: a section of code with a name that can be reused multiple times
Variable
a data structure with a name, that can store a value that might change while the program runs
2.1.3: be able to differentiate between types of error in programs (logic, syntax, runtime)
Keyword
Definition
logic error
a mistake by the programmer where the code runs and does what the programmer told it to do, but not what the programmer wanted it to do (e.g. add instead of subtract)
runtime error
an error that occurs when the code runs, but tries to do something impossible (e.g. divide by zero)
syntax error
a mistake by the programmer where the code doesn't follow the rules of the programming language. This prevents the code from running at all (e.g. missing brackets)
2.1.4: be able to design and use test plans and test data (normal, boundary, erroneous)
Keyword
Definition
actual result
what the program really does when a particular part of it is tested
boundary
a way of describing test data that is either the maximum or minimum acceptable value (e.g. "How old are you?": 0)
erroneous
a way of describing test data that isn't able to be converted into the right data type (e.g. "How old are you?": potato)
expected result
what the user would expect the program to do if it worked properly when testing a particular part of the program
extreme
a way of describing test data that is too big or too small compared to expected input data (e.g. "How old are you?": 1024)
normal
a way of describing sensible input test data that you'd expect the program to be able to cope with (e.g. "How old are you?": 15)
test data
the values that are provided by the user to test a particular part of the program
test plan
a table that records how a program is tested (description, test data, expected result and actual result)
2.1.5: be able to interpret error messages and identify, locate and fix errors in a program
Keyword
Definition
Debug
find and fix an error in a program
Error message
description of that caused the program to crash or not run
Line number
tells you which part of your code caused an error to occur
Step
run each line of code one by one to help you see what causes an error to occur
2.1.6: be able to determine what value a variable will hold at a given point in a program (trace table)
Keyword
Definition
Boolean
True or False
Character
Single letter, digit or punctuation mark (e.g. !)
Data type
Integer, boolean, real, character or string
Debug
find and fix an error in code
Integer
a whole number (e.g. 1)
Real
Decimal number (also known as float) (e.g. 1.432)
Step
run just one line of code and see what happens
String
Zero or more characters stored in order (e.g. "hello 123")
Trace table
shows the values stored in each variable after running each line of code in an algorithm or program
Value
the data stored in a variable
Variable
data structure with a name. Used to store a value that can change when the program runs
2.1.7: be able to determine the strengths and weaknesses of a program and suggest improvements
Keyword
Definition
Accessibility
how easy the program is to use for people with disabilities
Accuracy
how closely the program's output matches the correct and expected result
Memory use
how much RAM the program uses whilst running
Reliability
how frequently the program can solve a problem
Robustness
how the program copes when something happens that might make it crash
Speed
how quickly a program runs
Usability
how easy to understand and use a program is
2.2.1: understand the structural components of a program (variable and type declarations, command sequences, selection, iteration, data structures, subprograms)
Keyword
Definition
command sequence
lines of code that give instructions that will be executed in order
data structure
arrays, lists and records that can store multiple values
declaration
line of code that says what a variable will be called and what type of data it will store
iteration
lines of code that control how many times a section of code should be repeated
selection
lines of code that work out a boolean expression to decide which lines of code to execute next
subprogram
a section of code (procedure or function) with a name that performs a specific task
Type
integer, boolean, real, character or string
variable
data structure with a name. Used to store a value that can change whilst the program runs
2.2.2: be able to use sequencing, selection and iteration constructs in their programs
Keyword
Definition
Constructs
sequence, selection and iteration: the building blocks of all computer programs
Execute
run an instruction
Instruction
a line of code that can be executed
Iteration
instructions that control how many times a section of code will be executed
Selection
instructions that make a choice that affects what is executed next
Sequence
multiple instructions that are executed in a specific order
2.3.1: understand the need for, and understand how to use, data types (integer, real, Boolean, char)
Keyword
Definition
Boolean
a type of data which is either True or False
Casting
converting from one data type to another
Char
a single digit, letter or punctuation mark (e.g. *)
Integer
type of data which is a whole number (e.g. 1)
Real
type of data which is a number that's got a decimal point (e.g. 1.432). Also known as a float
2.3.2: understand the need for, and understand how to use, data structures (records, one-dimensional arrays, two-dimensional arrays)
Keyword
Definition
1D array
a data structure that is like a list of values.
2D array
a data structure that is like a list of lists or a grid / table
Array
a data structure that stores multiple values of the same data type in a specific order
Data structure
a record or array that stores multiple values
Index
the position of a value within an array
Length
the number of values inside an array
2.3.3: understand the need for, and how to manipulate, strings
Keyword
Definition
Cast
convert from one data type to another data type (e.g. string "2" to integer 2)
Character
an individual letter, digit or punctuation mark
Concatenate
join two strings together
Length
the number of characters within a string
String
data type used to store zero or more characters (e.g. "123N")
Substring
part of a string (at the start, end or anywhere within a larger string)
2.3.4: understand the need for, and how to use, variables and constants
Keyword
Definition
Assign
to set the value of a variable
Constant
a data structure which stores a value that is set in code which can be used (but not changed) while the code runs. Usually has a name in CAPITAL_LETTERS
Declare
to say that a variable exists (usually saying which data type it is going to store)
Identifier
the name of a variable or constant
Value
the data stored in a variable or constant
Variable
a data structure that can store a value that can change whilst the program runs. Usually has a name in snake_case_letters or camelCaseLetters.
2.3.5: understand the need for, and how to use, global and local variables when implementing subprograms
Keyword
Definition
Global variable
a variable that can be accessed from any part of the code because it was declared outside any sub program
Local variable
a variable that can only be accessed inside the sub program where it was declared.
Scope
the part of a program where you can access a variable or constant
Sub program
a part of a program (procedure or function) that has its own scope
2.4.1: understand how to write code that accepts and responds appropriately to user input
Keyword
Definition
Input
the data that the program accepts from the user
Response
the output from the program that's displayed to the user.
User
the person or people who will use the program when it's finished
2.4.2: understand the need for, and how to implement, validation
Keyword
Definition
Length check
a type of validation that checks if the expected amount of data is provided
Lookup check
a type of validation that checks if data matches a list of acceptable values
Presence check
a type of validation that checks if any data has been provided at all
Type check
a type of validation that checks if data is the expected data type
Validation
checking data to make sure that it is suitable to be processed or outputted
2.4.3: be able to write code that reads/writes from/to a text file
Keyword
Definition
Append
saving data onto the end of an existing file
Extension
the letters after the file name that indicates what type of data is stored in the file and which program should be used to open it
File
data stored on a device that can be accessed with a name, path and extension
Name
a description of the file
Path
the location of a file
Read
loading data from a file as input into a program
Runtime error
type of error that can occur if you attempt to open a file that doesn't exist
Write
saving data to a file as output from a program
2.5.1: understand the purpose of, and how to use, arithmetic operators (add, subtract, divide, multiply, modulus, integer division)
Keyword
Definition
-
subtraction operator
*
multiplication operator
/
division operator
+
addition operator
Arithmetic Operator
a symbol or symbols that performs a mathematical calculation using the data you seen next to them (e.g. + or -)
DIV
integer division (division ignoring the remainder)
MOD
modulus operator (the remainder after dividing)
2.5.2: understand the purpose of, and how to use, relational operators (equal to, less than, greater than, not equal to, less than or equal to, greater than or equal to)
Keyword
Definition
<
operator that checks if the first value is less than the second value
<=
operator that checks if the first value is less than or equal to the second value
<>
operator that checks if two values are not equal
==
operator that checks if two values are equal
>
operator that checks if the first value is greater than the second value
>=
operator that checks if the first value is greater than or equal to the second value
Relational Operator
symbol that compares two values
2.5.3: understand the purpose of, and how to use, logic operators (AND, OR, NOT)
Keyword
Definition
AND
a logic operator that combines two boolean inputs into a single output, which is True if both inputs are also True
Boolean expression
a question with a True / False answer
Logic Operator
Symbol or symbols that combine Boolean expressions
NOT
a logic operator that inverts an input so that the output is the opposite boolean value
OR
a logic operator that combines to boolean inputs into a single output, which is True if either or both inputs are True
2.6.1: understand the benefits of using subprograms and be able to write code that uses user-written and pre-existing (builtin, library) subprograms
Keyword
Definition
Abstraction
hiding unnecessary detail to focus on what's important. You don't need to know the detail of how a subprogram works in order to use it.
Builtin subprogram
a procedure or function that can be used 'out of the box' (e.g. print() in python). This means common tasks are easy achieve with very little code
Call
make a subprogram run
Decomposition
splitting a big problem into smaller sections. Different programmers can work on separate subprograms.
Definition
the lines of code that say exactly what a subprogram should do
Function
a subprogram that can be used more than once to calculate and return a value. It has a name which should describe what it does
Identifier
the name of a subprogram that should describe what it does in order to make code more readable
Library subprogram
a procedure or function that can be used if imported into your program. This saves programmers having to re-invent the wheel for every project
Procedure
a subprogram that can be used more than once to do something useful. It has a name which should describe what it does
Reuse
subprograms can be defined once but called many times
Subprogram
a section of code that has a name. It can be used more than once (e.g. procedure or function)
User-written subprogram
a procedure or function that you write yourself. This can be reused in the same or other projects.
2.6.2: understand the concept of passing data into and out of subprograms (procedures, functions)
Keyword
Definition
Function
subprogram that can have parameters and always returns a value
Parameter
data that can be passed from one part of code into a subprogram
Procedure
subprogram that can have parameters but doesn't return a value
Return value
data that is passed out of a function back to the part of code that called that function
Subprogram
a procedure or function (a reusable section of code with a name)
2.6.3: be able to create subprograms that use parameters
Keyword
Definition
Function
a subprogram that can receive zero or more parameters and always returns a value
Parameter
data passed into a subprogram that affects how it works. Treated as a local variable within that subprogram
Procedure
a subprogram that can receive zero or more parameters but never returns a value
Subprogram
a named section of code that can be reused (procedure or function)
