Programming Techniques

• What are the programming constructs?

  Sequence, selection, iteration
• What is sequence? Series of logical steps that are performed in a given order
• What are some common examples of sequence? Variable initialisation and print statements
• What is branching/selection? Instructions which can evaluate a Boolean expression and then jump the code to one or more alternative paths
• What are some common examples of selection? IF statements and CASE statements
• What is iteration? Section of code which can be repeated either a set number of times (count controlled) or a variable number of times based on the evaluation of a Boolean expression (condition controlled)
• What are the three main types of loops: Infinite, count controlled, condition controlled
• What is an infinite loop? Section of code which keeps repeating until the user terminates the program or it crashes
• What is a possible use of an infinite loop? An operating system continually checking for user input and responding accordingly until the device is turned off or reset
• When would a count controlled loop be used? When the number of necessary iterations is known
• When would a condition controlled loop be used? When the number of necessary iterations is not known but is based on a condition
• What is a branch? Instruction in a computer program that can cause the computer to begin executing a different instruction sequence, deviating from its default behaviour of executing instructions in order
• What does scope refer to? Area where a function or variable is visible and accessible to other code
• What is a global variable? Variable which can be used anywhere in the program
• What is a local variable? Variable which is defined and can only be used within one part of the program (normally a single function or procedure)
• Why should local variables be used wherever possible? Excessive and unnecessary use of global variables can make programs hard to test, debug and maintain