Component 2 Flashcards Textbook
What is an algorithm?
A series of instructions that solves a problem in a finite number of steps
What three criteria lead to a successful algorithm?
- Accuracy
- Consistency
- Efficiency
What does unambiguous mean?
Written in a way that makes it completely clear what is meant
What are the two ways to plan and design an algorithm?
- Visual (Using flow chart symbols)
- Text (Using a written sequence of instructions)
What is the difference between an algorithm and a problem?
Before you can write a program to solve a problem, you have to work out the algorithm first
What is a variable?
A storage location used to store a value; this could be text or a number. The value stored in the variable may change as the program is run.
What are the rules for a variable name?
- Must be written before a value is assigned to it
- Cannot start with a number
- Must not have spaces
- Must make sense in algorithm
What is ‘=’ in OCR pseudocode?
Assignment of a value to a variable
What is ‘==’ in OCR pseudocode?
Shows equality
What is the flow chart symbol for a terminator and what does it show?
- Oval / Rounded Rectangle
- Start or end of algorithm
What is the flow chart symbol for a process and what does it show?
- Rectangle
- Process in algorithm e.g. Calculating price
What is the flow chart symbol for a decision and what does it show?
- Diamond
- Have one of two answers; yes or no, true or false
What is the flow chart symbol for an input or output and what does it show?
- Parallelogram
- Shows data into algorithm or outputs from it
What does an arrow show in a flow chart?
- Sequence of steps in the algorithm
- Usually vertical or horizontal
What is a flow chart?
Visual representation of the sequence of steps in an algorithm
What is assignment?
Giving a variable or constant a value by linking a value to the identifier
What is an identifier?
A unique name given to a variable or constant in your algorithm which makes your algorithm easier to read and understand
What is pseudocode?
A structured, code-like language that can be used to describe an algorithm
What are keywords?
Used in pseudocode for common operators; written in capital letters
What are some example keywords?
INPUT- Getting values into the algorithm from user via keyboard
OUTPUT- Messages or results displayed on screen
What are the pseudocode arithmetic operators for addition, subtraction, multiplication and division?
+ , - , * , /
What are the pseudocode arithmetic operators for integer division and modulus?
DIV (only evaluates quotient which is the integer)
MOD (only evaluates remainder)
List all the comparison operators (and what they evaluate to)
< - Less than (True)
> - Greater than (False)
== - Same as (True)
!= - Not equal to (True)
<= - Less than or equal to (True True)
>= - Greater than or equal to (True False)
True or False: Arithmetic Operators are evaluated AFTER comparison operators
False, evaluated BEFORE.
What are the three Boolean operators?
AND - Checks both conditions are true or false
OR - Checks EITHER conditions is true
NOT - Reverses Boolean Value (e.g x>y = False, NOT reverses evaluation to True)
What is an operator?
Symbol that shows an operation
What are the three basic programming constructs ?
- Sequence
- Selection
- Iteration
What is an exponentiation?
Base integer is raised to power of exponent integer, Operator is ^
What are the two types of iteration?
- Condition- controlled loop
- Count-controlled loop
What is nesting?
Combining code together, putting a while loop inside a while loop
What is an array?
Data structure that allows storage of multiple items in a single variable
What is a subprogram?
Clear, independent blocks of code within a computer program which can be called and accessed by main program
What is ‘call’?
Starting the subprogram
What are subprograms which return values known as?
Functions
What are subprograms which don’t return values known as?
Procedures
What is decomposition?
Breaking problem down into smaller sub-problems until these tasks are solved
What is a string?
A sequence of characters surrounded by quotation marks
What is concatenation?
Merging or joining two strings together using a concatenation operator (+)
What is abstraction?
Process of removing unnecessary details from a problem
What is time efficiency?
The number of steps to complete the algorithm
What is space efficiency?
The amount of memory required to complete the algorithm
What is brute force?
Process that tries all possible alternatives to find a solution
What is an input?
Data that a program receives and processes
What sources can inputs come from?
- User Input
- Files
- Sensors
- Networks
What is an output?
Results of a program’s processing
How can an output be presented?
- On Screen
- Printed Out
- Sent to other devices or programs
How do you make use of data retrieved by an input function?
- Assign a return value to a variable which allows program to store and manipulate input data
What is a sequence?
Executing a series of statements in a specific order, following linear flow
What is selection?
Enables program to make decisions based on conditions
What is iteration?
Allows a set of instructions to be repeated multiple times as long as certain condition is true
What happens when sequence fails and instructions are executed in wrong order?
- Program’s behavior can deviate from intended logic causing logic errors, unexpected results or crashes
What are the two types of iteration?
Count-controlled
Condition-controlled
What is count-controlled iteration?
Number of times the loop is executed is predetermined before the loop starts
What is condition-controlled iteration?
Loop continues until a certain condition is met
What are the arithmetic operators and what do they do?
+ - Addition
- - Subtraction
* - Multiplication
/ - Division
^ - Exponentiation (raises to the power)
DIV - Quotient (returns integer)
% - Modulus (also MOD, returns remainder)
What are the comparison operators and what do they do?
== - equal to
!= - not equal to
< - less than
<= - less than or equal to
> - greater than
>= - greater than or equal to
What are the Boolean operators and what do they do?
AND - Returns true if both operand are true
OR - Returns true if either operands are true
NOT - Reverses logic state of its operand
What are the 5 common data types?
Integer - Whole Numbers
Float - Decimal Numbers
Boolean - True/False Values
Character - Single alphanumeric character
String - Sequence of characters
What is string concatenation?
Process of joining two strings together using the ‘+’ operator
How can you convert other variables into string for string concatenation?
Create a new string variable and assign it to to_string(variable_name)
How to use substrings?
Use the variable.substr(num1, num2) in which num1 is the index you should start at, including 0, and num2 is the number of characters to include afterwards
