Templates Generic Programming

The Issue Want function to find the larger of two values

Up Until Now Need multiple versions: int largest(int num1, int num2) { //return largest } double largest(double num1, double num2) { //return largest } Person largest(Person p1, Person p2) { //return largest }

Templates Templated Functions Specify way to build a function Applies to any data type

Template Declaration template<class/typename T> class/typename interchangeable T is a type parameter – can be anything Can have multiple type parameters

Type Parameter Type parameter used to code template: Whatever T is… We return one We take two as parameters

Instantiation Template instantiated when needed at compile time New version of code created for each type template applied to

Template Including Template functions must have full code in .h file Needed at compile time for instantiation Don’t have to worry about multiple versions

Templates All T's must be same type No conversions done

Templates All T's must be same type No conversions done Can force type

Operators & Members Template can assume any operators/members it wants Compile error if type doesn't support

Non Templated Params Can have normal parameters in template function

Templated Variables Can use template type as local variable type

Templated Class Class can be template Type of variable includes instantiation type:

Templated Class Functions Function definitions must be template Scope resolution must include template

Templates of Templates Template can instantiate on templated type:

Multiple Types Template can have multiple types: