outline Class and Object-Oriented Programing –Encapsulation and inheritance Example –Commission Employee –Encapsulation and inheritance Strings and Formatting In-class assignment –Derived class –Access scope

Class Procedural vs Object-oriented User-defined types (programmer-defined types) class Encapsulation (private and public) Member Variables and access modifiers Member Methods Constructor Constructor and method overloading –Method overloading: two or more methods have same name but with different number or type of parameters. Using class

ref class Square { public: Square (int d) { Dims = d; } int Area () { return Dims*Dims; } int Dims; };

Use ref class Square ^sqr1 = gcnew Square(); // a handle sqr1->Dims = 5; int area = sqr1->Area (); Or: Square sqr2; // a local or a stack instance sqr2.Dims = 3; int i = sqr2.Dims; int area = sqr2.Area ();

Example CommissionEmployee firstName lastName socialSecurityNumber grossSales commissionRate Read/write these variables getXXX() / setXXX() earnings() print() private and public accesses

Constructor –Initialize the object at instantiate –A special method: called at object creation by gcnew(), same name as the class, no return (not defined with void either), can take any number of parameters, public Constructor overloading class testclass { public: testclass () { x = y = 0; } testclass(Int32 a) { x = y = a; } // x =a; y = 10; testclass(Int32 a, Int32 b) { x = a; y = b; } private: Int32 x; Int32 y; };

testclass ^a1 = gcnew testclass(100); testclass ^a2 = gcnew testclass(); testclass ^a3 = gcnew testclass(100, 2);

static class methods and variables Static variable in a class: –only one copy of the variable is created, and it is shared by all the instances of the class. (not associated with an instance) –Initiated only at the first time the class is instantiated. ref class staticVar { static int counts = 3; }; Static method in a class: –the method is accessible without the need to instantiate the class. –Use only static member variables. Public: static int get_x () { return x; } –To use it: Console::WriteLine(className::get_x());

Inheritance Code reuse Base class and derived class in C++ this and class scope(::) in C++ Method overriding –A method in the derived ref class has an identical signature to the base ref class Access modifiers protected

using namespace System; // Base class ref class Square { public: int Area () { return Dims*Dims;} int Dims; }; // Derived class Ref class Cube : public Square { public: int Volume() { return Area()* Dims; } };

// inheritance in action void main(void) { Cube ^cube = gcnew Cube (); cube->Dims = 3; Console::WriteLine(cube->Dims); Console::WriteLine(cube->Area()); Console::WriteLine(cube->Volume()); }

Access modifiers Public –Accessible by external functions and methods –Accessible to derived ref classes Private –Not accessible by external functions and methods –Not accessible to derived ref classes Protected –Not accessible by external functions and methods –Accessible to derived ref classes

Example CommissionEmployee BasePlusCommissionEmployee firstName lastName socialSecurityNumber grossSales commissionRate earnings() print() baseSalary earnings() print()

Strings and Formatting in C++/CLI us/library/system.string.aspxhttp://msdn.microsoft.com/en- us/library/system.string.aspx public: static String^ Format( String^ format,... array ^ args ) Format:{index[,length][:formatString]} {0}, {0, 10}, {0, -10}, {0, -10:D6}, {0,-10:f} double d = 134; int a = 30; Console::WriteLine("{0,-10:f}{1,-10}",d, a);

String^ dateString1 = "1"; String^ fmtString = String::Format("{0,10}",dateString1); // -10 to left, 10 to right Console::WriteLine(fmtString); int dateString2 = 1; String^ fmtString = String::Format("{0,-10:D6}",dateString2); Console::WriteLine(fmtString); String^ result = nullptr; result += String::Format("{0,10}", L"X4"); result += String::Format("{0, 10:D6}", dateString2); result += String::Format("{0,10}", L"end"); Console::WriteLine(result);

String^ result1 = L"X4"; String^ result2 = String::Format("{0} ", dateString2); String^ result3 = L"end"; Console::WriteLine("{0,10} {1, 10} {2,10}", result1, result2, result3); fmtString = String::Format("{0,10} {1, 10} {2,10}", result1, result2, result3); Console::WriteLine(fmtString); fmtString = String::Format("{0,10} {1, 10} {2,10}", result1, dateString1, result3); Console::WriteLine(fmtString);