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6.1.1: be able to use decomposition and abstraction to analyse, understand and solve problems
Keyword
Definition
abstraction
removing unnecessary detail in order to focus on what's most important
decomposition
breaking down a problem into smaller sections to make it easier to solve
6.1.2: be able to read, write, analyse and refine programs written in a high-level programming language
Keyword
Definition
assembly
example of a low level programming language
high level
type of programming language where a small amount of code can solve large problems by hiding unnecessary details about how the CPU and memory are managed
low level
type of programming language which can require a large amount of code to solve even small problems because you have complete control over the CPU and memory management
programming language
a way of describing data structures and algorithms to tell a computer how to solve a problem
python
example of a high level programming language
6.1.3: be able to convert algorithms (flowcharts, pseudocode) into programs and convert programs into algorithms
Keyword
Definition
decision
diamond seen in a flowchart whenever the algorithm has to make a choice what to do next
flowchart
diagram which shows each stage of an algorithm
input
parallelogram seen in a flowchart whenever data is entered into an algorithm
output
parallelogram seen in a flowchart whenever data is sent out or displayed from an algorithm
process
rectangle seen a flowchart wherever a calculation takes place
program code
algorithm written in a formal way so that it can be run on a computer
pseudocode
informal written description of a program which does not require any strict programming syntax
syntax
rules for a programming language
terminator
rounded rectangle seen at the start and end of each flowchart
6.1.4: be able to use techniques (layout, indentation, comments, meaningful identifiers, white space) to make programs easier to read, understand and maintain
Keyword
Definition
comments
code is easier to read when each line or section of code is described in a way that helps other programmers understand what it does
identifiers
code is easier to read when variables, constants and sub programs have names which describe what they store or do
indentation
code is easier to read when tabs or spaces are used to move blocks of code across to the right. This is necessary in python but optional in other programming languages
layout
code is easier to read when it is organised into sections e.g. imports, constants, global variables, sub programs then the main program code
whitespace
code is easier to read when blank lines are used to break the code into logical paragraphs
6.1.5: be able to identify, locate and correct program errors (logic, syntax, runtime)
Keyword
Definition
logic error
a type of error which occurs when the program does what it's told to do, but the programmer told it to perform the wrong calculation
runtime error
a type of error which occurs when the program crashes because it attempts to do something impossible
syntax error
a type of error which occurs when the program will not run at all because the programmer has broken the rules of the programming language
6.1.6: be able to use logical reasoning and test data to evaluate a program's fitness for purpose and efficiency (number of compares, number of passes through a loop, use of memory)
Keyword
Definition
comparisons
the number of items of data an algorithm has to check before it finishes solving a problem
efficiency
how good one algorithm is at solving a problem compared to another
iterations
the number of times an algorithm has to repeat a sequence of instructions before it finishes solving a problem
logical reasoning
being able to compare one algorithm with another and explain which is most suitable for solving a problem
memory use
the number of different data values an algorithm has to store at the same time in order to solve a problem
test data
the values given to an algorithm as input in order to see what outputs it gives and how long it takes to solve a problem
6.2.1: understand the function of and be able to identify the structural components of programs (constants, variables, initialisation and assignment statements, command sequences, selection, repetition, iteration, data structures, subprograms, parameters, input/output)
Keyword
Definition
assignment
setting the value of a variable at any time in a program e.g. score = 1
command sequence
part of an algorithm where multiple instructions are carried out in a particular order
constant
named value which is set once but can be used multiple times e.g. MAX_SCORE = 10
data structure
a named area of memory which stores multiple values (e.g. scores = [1,2,3])
initialisation
setting the value of a variable or constant at the start of the program e.g. score = 0
input
data which goes in to an algorithm or program e.g. input(...)
iteration
part of an algorithm that repeats instructions for each value in a data structure e.g. for ... in ...
output
data which comes out from an algorithm or program e.g. print(...)
parameter
a value which is passed into a sub program e.g. def square(size):
repetition
part of an algorithm that is run a set number of times or whilst a condition is met e.g. while lives > 0:
return value
a value which is passed out from a function
selection
part of an algorithm where a condition is checked to see which instructions are run next e.g. if ... :
sub program
a named part of a program which can be called multiple times (either a procedure or a function) e.g. def square():
variable
named memory location which stores a value which can be set and used multiple times e.g. score = 0
6.2.2: be able to write programs that make appropriate use of sequencing, selection, repetition (count-controlled, condition-controlled), iteration (over every item in a data structure) and single entry/exit points from code blocks and subprograms
Keyword
Definition
code block
section of code which is all indented by the same amount
entry point
the first line of code which is executed
exit point
the last line of code in a code block or subprogram to be executed
function
named section of code which can be called multiple times and always returns a value
iteration
using FOR to loop through each value in a data structure (e.g. list or string)
procedure
named section of code which can be called multiple times and never returns a value
repetition
using FOR or WHILE to allow code to repeat a set number of times or whilst a condition is met
selection
using IF to allow code to make a choice
sequence
multiple lines of code that have to be executed in order
subprogram
a procedure or function
6.3.1: be able to write programs that make appropriate use of primitive data types (integer, real, Boolean, char) and one and two-dimensional structured data types (string, array, record)
Keyword
Definition
array
data structure which stores a fixed number of values of the same data type arranged in order
boolean
True or False
char
individual letter, symbol or digit
integer
a whole number
list
data structure which can grow or shrink to store as many values as required, keeping them in order
primitive data type
the type of data for a variable or constant which holds an individual value
real
a number with a decimal point
record
data structure which stores multiple values of different data types arranged in order
string
data structure which stores multiple characters arranged in order
structured data type
the type of data for a variable or constant which holds multiple values
6.3.2: be able to write programs that make appropriate use of variables and constants
Keyword
Definition
assignment
setting the value of a variable
constant
named value which is set once but remains the same whilst the program runs
identifier
the name of a variable or constant
initialisation
setting the value of a variable or constant for the first time
naming convention
set of rules for choosing suitable variable or constant names
value
the data stored in a variable or constant
variable
named memory location which can store a value which can change as the program runs
6.3.3: be able to write programs that manipulate strings (length, position, substrings, case conversion)
Keyword
Definition
case conversion
changing a string from uppercase to lowercase or the other way round
character
individual symbol, letter or digit that forms part of a string
concatenation
joining multiple strings together into a single string
length
the number of characters that makes up a string
lowercase
string without any capital letters
position
number which identifies where you need to look in a string to find a specific character (starting from 0 at the beginning)
string
data structure which stores multiple characters in order
substring
getting a string of characters from inside another string
uppercase
string made up of all capital letters
6.4.1: be able to write programs that accept and respond appropriately to user input
Keyword
Definition
boolean expression
a question with a True or False answer
output
using print(...) to display a message to the user
selection
using if to decide what to run next based on a boolean expression
user input
using input(...) to ask the user a question
6.4.2: be able to write programs that read from and write to comma separated value text files
Keyword
Definition
append
saving data on to the end of an existing file
comma separated value
file that can be opened by spreadsheet software because a table of data is stored as lines of text with commas between each value
read
loading data from a file
text file
file that can be opened in a editor like notepad where data is stored in a way that can be understood by humans
write
saving data to a file, overwriting what's already there
6.4.3: understand the need for and be able to write programs that implement validation (length check, presence check, range check, pattern check)
Keyword
Definition
input data
the values that are sent into a program (e.g. from the user or a file)
length check
type of validation that checks the number of characters in input data
pattern check
type of validation that checks that input data matches a specific sequence of letters, symbols or digits
presence check
type of validation that checks to see if input data is empty or not
range check
type of validation that checks that input data is between minimum and maximum values
validation
checking data (often user input) to see if it is suitable to be processed by a program
6.4.4: understand the need for and be able to write programs that implement authentication (ID and password, lookup)
Keyword
Definition
authentication
checking that a user is allowed to log in to a computer system
ID
unique identification data such as username, number or email
lookup
checking to see if a users ID and password matches a list of approved user details in a database or file
password
secret data which can be entered and checked when logging in to a computer system
6.5.1: be able to write programs that use arithmetic operators (addition, subtraction, division, multiplication, modulus, integer division, exponentiation)
Keyword
Definition
-
arithmetic operator which subtracts one number from another
-=
arithmetic operator which decreases a variable by a given amount
*
arithmetic operator which multiplies one number by another
**
arithmetic operator which raises a number to a power
*=
arithmetic operator which multiplies a variable by a given amount
/
arithmetic operator which divides one number by another
//
arithmetic operator which divides one number by another giving the result as an integer, always rounding down
/=
arithmetic operator which divides a number by a given amount
%
arithmetic operator which finds the modulus (remainder after integer division)
+
arithmetic operator which adds two numbers together
+=
arithmetic operator which increases a variable by a given amount
arithmetic operator
symbol or characters used to perform a mathematical process on input data
6.5.2: be able to write programs that use relational operators (equal to, less than, greater than, not equal to, less than or equal to, greater than or equal to)
Keyword
Definition
!=
relational operator which evaluates to True if two values are not equal
<
relational operator which evaluates to True if the first value is less than the second
<=
relational operator which evaluates to True if the first value is less than or equal to the second
==
relational operator which which evaluates to True if two values are equal
>
relational operator which evaluates to True if the first value is less than the second
>=
relational operator which evaluates to True if the first value is greater than or equal to the second
relational operator
symbol or characters which compare two values giving the result as a boolean True or False
6.5.3: be able to write programs that use logical operators (AND, OR, NOT)
Keyword
Definition
and
logical operator with two inputs which only evaluates to True if both inputs are True
boolean expression
question which has an answer of either True or False
logical operator
symbol or character which can combine boolean expressions or values using AND, OR or NOT
not
logical operator which inverts a single boolean input from True to False or vice versa
or
logical operator with two inputs which evaluates to True if either or both inputs are True
6.6.1: be able to write programs that use pre-existing (built-in, library) and user-devised subprograms (procedures, functions)
Keyword
Definition
built-in subprogram
a type of pre-existing subprogram which you can use in python without having to import any modules or defining it yourself (e.g. input / print)
function
a type of subprogram which can have parameters by always returns a value
library subprogram
a type of pre-existing subprogram which you can use in python if you import a module (e.g. random or turtle)
pre-existing subprogram
a subprogram which you can use with python without having to define it yourself (e.g. built-in or library subprogram)
procedure
a type of subprogram which can have parameters but never returns a value
subprogram
either a procedure or function (a named section of code that can be called multiple times)
user-devised subprogram
a type of subprogram which you have defined in your own python code using def
6.6.2: be able to write functions that may or may not take parameters but must return values, and procedures that may or may not take parameters but do not return values
Keyword
Definition
function
type of subprogram which always returns a value
parameter
data passed into a subprogram to customise how it works
procedure
type of subprogram which never returns a value
return value
data passed out of a function back to the part of code which called it
subprogram
either a procedure or function (named section of code which can be customised with parameters and called multiple times)
subprogram call
part of the code which causes a subprogram to actually run
subprogram definition
part of the code which tells the code what to do when a subprogram runs
6.6.3: understand the difference between and be able to write programs that make appropriate use of global and local variables
Keyword
Definition
global variable
type of variable which can be accessed from any block of code in a program
local variable
type of variable which can only be accessed from within the scope of a subprogram or block of code
parameter
value passed into a subprogram which then behaves like a local variable for the scope of that subprogram
scope
the block(s) of code where a variable can be accessed (either global or local)
variable
named memory location which can store a value which can change when the program runs
