Control Structures - no methods

Ruth Hyndman
Flashcards by Ruth Hyndman, updated more than 1 year ago
Ruth Hyndman
Created by Ruth Hyndman over 5 years ago
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Flashcards on the Control Structures unit from the SSD AS course by CCEA.

Resource summary

Question Answer
Name 3 control structures Sequential Selection Repetition/Iteration
Describe the Sequential control structure. A list of instructions are carried out one after another in a predetermined order. No actions can be skipped.
Describe the Selection control structure. The program control branches to specific flows based on whether or not a condition is true.
Name 2 key selection constructs There are 2 key selection constructs, if statements and switch statements.
What does an IF statement do? An if statement carries out a set of statements if a condition is true and ignores them if a condition is false. They use the key words if, else and else if.
What is an IF ELSE statement? This is an extenstion of the IF statement. It will execute a block of code when a condition is true and an alternative block of code if the condition is false.
What is an ELSE IF statement? This is very similar to an else statement but has an extra condition. It will run block of code if a condition is true, a different one if the first was false and the second condition is true and so on.
What is a Switch statement? This allows a variable to be tested against a list of values. The value changes the control flow of program execution via a multiway branch. Switch statements use the keywords switch, case, default and break. Break must be used in-between cases.
What are the benefits of Switch statements? They are effective when comparing one variable against many values. Often they are easier to read than a collection of ifs and else ifs.
Describe the Repetition control structure. The program control repeats a set of statements until a condition is met. AKA iteration
What does a For loop do? A For loop executes its statements a specified number of times. They are used whenever the number of repetitions is known or can be calculated. They are useful for processing data or arrays.
What does a While loop do? A While loop executes its statements as long as its condition is true. They are known as pre-test loops as the condition is checked before any statements are executed. If the condition is always true, an infinite loop will occur.
What are the benefits of While loops? The fact that it is a pre-test loop means that the loop can be exited without any of its statements being executed. This makes it useful for validation.
What is a Do While loop? A Do While loop executes its statements as long as its condition is true. It differs from the While loop because it is a post-test loop meaning the condition check takes place after all the statements have been executed. If the condition is always true, an infinite loop will occur.
What are the benefits of Do While loops? The fact that it is a post-test loop means that all of its statements will be executed at least once.
What is the benefit of Repetition statements. Statements do not have to be written over and over as they can be repeated. This cuts down on code and simplifies the program.
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