Variables  A piece of memory set aside to store data  When declared, the memory is given a name  by using the name, we can access the data that sits in memory  we can retrieve the value, we can change the value

Variables a variable must be declared before it can be used type name; type name = value; type - the type of data to be stored – integers (int, long) – real numbers(float, double) – characters (char) – logic (bool) name - a legal identifier value - a literal value

Variables int x; int y = 0; double avgSpeed = 5.9; boot isReady = false;

Variables Once declared, you just use the name to access the data double avgSpeed = 3.5; double time = 100.0; double distTravelled = 0.0; cout << avgSpeed; avgSpeed += 1; cout << avgSpeed; distTravelled = avgSpeed * time;

Functions Functions are blocks of code that perform a specific task Functions are assigned a name and can be called many times Functions can accept input and provide an output Functions MUST be declared before they can be used Functions that are declared MUST also be defined

Functions Declaring – done before use, so let's put it before our main return name(param,param,...); – return - the type of output we expect void means no output, or int, float, double, long, bool mean return of that type – name - a legal identifier – param - a variable to represent the input

Functions void printMessage(); void printNumber(int num); bool isRobotWorking(); double areaOfCircle(double radius); The declaration is also called the prototype

Functions If we declare a function, we must also define it – give it some instructions to complete its task We usually define it near the end of out code, after the main the definition starts with the same prototype as before – has a block of code – if an output is needed, must call return

Functions int myFunction(int param1, int param2); int main(){ } int myFunction(int param1, int param2){ return param1 + param2; }

Functions Inside the definition we can have any legal code – variable declarations – operations – calls to other functions The parameter variables exist as if they were declared inside the function A function that has an output MUST call return – once return is called, the function is over

Functions Using functions – we use functions to wrap up a block of code – this block of code is then simply called by its name – the function can be called once, or multiple times – when a function is called, we jump to its definition and execute its code, once finished we return to where the call originated and continue from there

Functions Parameters – parameters are variables that hold the input to the function – when you call a function with parameters you MUST provide values to those variables int getAvg(int num1, int num2); – to call getAvg(3,4); int y = 2; int x = 3; getAvg(y,x);

Functions Returns (output) – functions that return a value are used in the same manner as variables – the value can be output to the screen, put into a variable, sent into another function, used in an expression cout << getAvg(3,4); double y = areaOfCircle(r); int minTemp = calcTemp(getPressure());

Examples Lab tut Online notes

If statements Put a condition on a block of code IF the condition is TRUE, the code will be executed if(x > 3){ cout << “Success!” << endl; } allows us to program decisions and choice

If Statements We can also include other options The computer will evaluate each options condition until it finds one that is true once a successful condition is met, the IF statement is finished options are written else if a “catch-all” option is written else

if (grade 79){ cout << “you got an A”; } else if (grade > 69){ cout << “you got a B”; } else if (grade > 59){ cout << “you got a C”; } else if (grade > 49) cout << “you got a D”; else{ cout << “you FAILED”; } cout << “endl”;

While Loops Allows us to attach a condition to a block of code The code will be executed over and over again, until the condition becomes false if the condition never becomes false, the code never stops if the condition is never true, the code will never be executed

While Loops //stores data, return false when bank is full bool storeData(double in); ….... bool readData = true; while(readData == true){ cout << “enter your number: “ ; cin >> inputData; readData = storeData(inputData); }

Logical Expressions Evaluate to either true or false operators – >,>=, <, <=, !, == expressions can be combined – && means both conditions are true – || means either condition is true REMEMBER OUR TRUTH TABLE!?!?

Terms Keyword Identifier literal Types Syntax Comments Loop Condition Prototype Declaration Parameter Expression Logic Expression Variable Function Compiler Control Statement Operator Definition

Operators << >> > < >= <= == = && ! != ++ – += -= ( ) { } ||

Rules Identifiers - letters, numbers, _ - can't start with number, or _ - should make sense Semi-colons - all expressions end with a ; Declaration - Functions and variables must be declared, before they are used Brackets - if you start a bracket, finish a bracket