2.2 problem solving and programming

sequence

\-code is executed line by line, top to bottom

selection/branching

\-a particular block of code runs if a specific condition is met

\-IF and ELSE statement

iteration

\-count controlled

\-condition controlled

\-FOR, WHILE, REPEAT UNTIL

count controlled iteration

\-block of code executed a certain amount of times

condition controlled iteration

\-block of code is executed until a condition is met

recursion

\-a subroutine that calls itself during execution

\-continues until a stopping condition is met

recursion advantages

\-can be represented in fewer lines of code

\-some functions are easier to express recursively

recursion disadvantages

\-risk of stack overflow if memory runts out

\-difficult to trace

local variable

\-can only be accessed within which they were defined

\-deleted once the subroutine ends

\-multiple with the same name can exist within different subroutines

local variable advantages

\-memory efficient

local variable disadvantages

\-harder to trace where values are passed

global variable

\-can be accessed across the whole program

\-not deleted until the program terminates so may use more memory and unnecessarily

global variable advantages

\-easier to program

\-simpler to follow

\-easier to debug

global variable disadvantages

\-memory inefficient

\-not good programing technique

modular programming

\-technique used to split large complex problems into smaller self contained modules

modular programming advantages

\-easier to manage a project and divide tasks within a team

\-each component can be dealt with individually simplifying the process of testing and maintenance

\-improves reusability of components

top down design

\-problem is broken down into sub problems until each is represented as an individual, self contained module that performs a certain task

functions and procedures

\-blocks of code that perform a certain task

\-functions return a value, procedures do not

\-parameters can be passed by value or by reference

passing parameters by values

\-a copy of the value is passed into the subroutine and discarded at the end

\-its value outside the subroutine is unaffected

passing parameters by reference

\-address of the parameter is given to the subroutine

\-value of the parameter will be updated at the given address

Integrated development environment (IDE)

\-program that provides a set of tools to make it easier to write, develop and debug code

features of IDEs

\-stepping

\-variable watch

\-breakpoint

\-source code editor

\-debugging tools

\-colour coded syntax

Class (OOP)

\-template for an object

\-define the state (attribute) and behaviour (method) of an object

object (OOP)

\-instance of a class

Constructor (OOP)

\-creates an instance of an object from a class

inheritance (OOP)

\-when a child class take on attributes/methods from a parent class

encapsulation

\-prevents attributes from being directly accessed

decomposition

\-breaking down a problem into smaller sub problems that can be represented as a self contained subroutine

advantages of problem decomposition

\-makes projects and teams easier to manage

\-modules can be designed, developed and tested individually

\-modules can be developed in parallel

divide and conquer method

\-problem is halves with every iteration

\-each subproblem is solved, usually recursively

\-solutions to the subproblems are recombined/merged

divide and conquer

\-simplifies complex problems very quickly

\-applied in quick sort, merge sort and binary search

backtracking

\-finding a solution to a problem by building on visited paths that are known to be correct

\-once a path is found to be invalid the algorithm backtracks to the previous stage

data mining

\-used to identify patterns or outliers in large data sets

\-finds trends and correlations that aren’t immediately obvious

\-can be used to predict future trends

heuristics

\-finds an approximate solution when finding the best solution will take too long

performance modeling

\-simulating the behaviour of a model under different circumstances

\-cheaper, safer, less time consuming method of testing appliances

visualisation

\-data is presented in a way that is easier for humans to understand