1. Monday, 10/14/02, Slide #1 CS 106 Intro to CS 1 Monday, 10/14/02  QUESTIONS??  Today: More on classes!  Reading: None new  Exercises: Implement and test a function Argument for the class Complex, as discussed today.  New files/handouts: None new

2. Monday, 10/14/02, Slide #2 Constructors: Different kinds  Generally, should always have a default constructor:  ClassName( ) { }; Empty body can be defined ‘in-line’ in header file  Should include constructors to handle each of the ways that clients might specify initial values. Generally declare in header file, define in initialization file:  Complex(float initReal, float initImag); Lets user supply initial values for real and imaginary parts  Complex(float initReal); Lets user supply initial value for real part (imaginary part is set to zero)  This constructor can also be viewed as a type conversion function -- changing a float object to type Complex

3. Monday, 10/14/02, Slide #3 Default parameters: Making constructors (and other functions) more flexible  Here is another way to declare and define the initializing constructor for Complex:  In header file: Complex (double initReal = 0; double initImag = 0);  In implementation file: Complex::Complex(double initReal, double initImag) {real = initReal; imag = initImag; }  Permits user to omit arguments with default values: all or leave off one or more rightmost arguments Note difference!

4. Monday, 10/14/02, Slide #4 More on constructors with default parameters  Using previous constructor, following client declarations are all legal:  Complex a(1.1, 2.2);// a = 1.1 + 2.2 i  Complex b(3.3);// b = 3.3 + 0 i  Complex c; // c = 0 + 0 i  This constructor serves as initializing and default constructor and conversion function for real numbers!  Can’t omit earlier arguments and keep later ones:  Complex d(, 4.4) //illegal -- missing 1st argument

5. Monday, 10/14/02, Slide #5 Kinds of member functions  Constructors and destructors:  To create and destroy class objects  Destructors deallocate memory when a class object goes out of scope -- simple destructors are provided by the system -- these are fine for us right now.  Inspectors:  To return attributes of an object  Mutators:  To set or change attributes of an object  Facilitators:  To use an object to perform an action

6. Monday, 10/14/02, Slide #6 Examples for class Complex  Inspectors:  To return attributes of an object  Possible Complex inspectors might return: real part, imaginary part, magnitude, angle with x-axis  Mutators:  To set or change attributes of an object  Possible Complex mutators might: Input an object, alter the real or imaginary parts of an object, set object to zero  Facilitators:  To use an object to perform an action  Possible Complex mutators might: Do complex arithmetic, output object to monitor