Fundamental Programming Concepts (OCR GCSE Computer Science)
Revision Note
Written by: Robert Hampton
Reviewed by: James Woodhouse
Taking an algorithm and turning it into code, in any language, requires an understanding of several basic programming concepts such as:
Variables
Constants
Assignment
Operators
Inputs
Outputs
Variables, Constants & Assignments
What is a variable?
A variable is a named memory location that holds data that during the execution of a program, the data can change
Variables can store a variety of different types of data such as numbers, text or true/false values
To store data in a variable, the process of assignment is used
What is a constant?
A constant is fixed data that during the execution of a program cannot change
A constant can store a variety of different types of data, similar to variables
Pi is an example of a mathematical fixed value that would typically be stored as a constant
What is assignment?
Assignment is the process of storing data in a variable or constant under a descriptive name
Assignment is performed using the '=' symbol
Assigning variables & constants
Concept | OCR exam reference | Python |
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Variables |
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Constants |
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Operators, Inputs & Outputs
What is an operator?
An operator is a symbol used to instruct a computer to perform a specific operation on one or more values
Examples of common operators include:
Arithmetic
Comparison
Boolean (AND, OR and NOT)
Arithmetic
Operator | OCR exam reference | Python |
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Addition |
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Subtraction |
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Multiplication |
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Division |
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Modulus (remainder after division) |
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Quotient (whole number division) |
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Exponentiation (to the power of) |
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Comparison
Operator | OCR exam reference | Python |
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Equal to |
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Not equal to |
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Less than |
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Less than or equal to |
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Greater than |
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Greater than or equal to |
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Examples
Operator | OCR exam reference | Python |
|---|---|---|
Addition |
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Multiplication |
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Modulus |
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Quotient |
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Exponentiation |
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Equal to |
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Not equal to |
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Greater than or equal to |
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AND |
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What is an input?
An input is a value that is read from an input device and then processed by a computer program
Typical input devices include:
Keyboards - Typing text
Mice - Selecting item, clicking buttons
Sensors - Reading data from sensors such as temperature, pressure or motion
Microphone - Capturing audio, speech recognition
Without inputs, programs are not useful as they can't interact with the outside world and always produce the same result
What is an output?
An output is a value sent to an output device from a computer program
Typical output devices include:
Monitor - Displaying text, images or graphics
Speaker - Playing audio
Printer - Creating physical copies of documents or images
Area of a rectangle program
OCR exam reference |
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Python |
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Worked Example
A cinema calculates ticket prices based on age category
Adult = £13.00
Child = £7.50
The program asks the user to enter their age and calculates the cost of their ticket
A simple algorithm is used
adult = 13.00
child = 7.50
age = input("What is your age: ")
if age > 18 then
total_cost = adult
else
toal_cost = child
end if
print(total_cost)
The cinema decides to add a discount of 25% to customers who come to the cinema on 'Sunday evening'
Identify all the additional inputs that will be required for this change to the algorithm [2]
How to answer this question
What new information is needed?
Answer
day
time
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