Iterator: A way to sequentially access ( traverse ) each object in a container or collection. - Access is done as needed, not necessarily at once.

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1 CSE 12, Week Seven, Lecture One Iterator: A way to sequentially access ( traverse ) each object in a container or collection - Access is done as needed, not necessarily at once. - Implemented by a private pointer advancing to the next item or prior item as needed. o Implementation differs based on container o class List { Node * front; Node * iterator; } - Operations (customize as needed): o getcurrentitem returns item at iterator return iterator->data; o hasnext returns true if there is a next item o getnextitem iterates to the next item iterator = iterator->next; return getcurrentitem(); o hasprior returns true if there is a prior item o getprioritem iterates to the prior item iterator = iterator->pre; return getcurrentitem(); o reset resets private pointer to first item. iterator = iterator->front;

2 class Parent { int aaa; int bbb; int ccc; class Private : private Parent { int ddd; int eee; int fff; class Protected : protected Parent { int ggg; int hhh; int iii; class Public : public Parent { int jjj; int kkk; int lll; int main () { Parent MomDad; // bytes Private Eye; // bytes Protected Wilderness; // bytes Public Property; // bytes // scope resolution main Parent:: Public:: MomDad.aaa = 10; MomDad.bbb = 10; MomDad.ccc = 10; Eye.aaa = 10; Eye.bbb = 10; Eye.ccc = 10; Eye.ddd = 10; Eye.eee = 10; Eye.fff = 10;

3 Wilderness.aaa = 10; Wilderness.bbb = 10; Wilderness.ccc = 10; Wilderness.ddd = 10; Wilderness.eee = 10; Wilderness.fff = 10; Wilderness.ggg = 10; Wilderness.hhh = 10; Wilderness.iii = 10 Property.aaa = 10; Property.bbb = 10; Property.ccc = 10; Property.jjj = 10; Property.kkk = 10; Property.lll = 10; aaa = 10; bbb = 10; ccc = 10; ddd = 10; eee = 10; fff = 10; ggg = 10; hhh = 10; iii = 10; jjj = 10; kkk = 10; lll = 10; }

4 Constructor rules: - Don t have a return type. - More than one can exist per class. o Distinguished by parameter list (overloading) - Called when an instance comes into existence: o RTS objects: : Local objects (default or overloaded constructor) Parameter objects ( constructor) Reference parameters are not new objects o constructors are called for reference parameters. Return result objects ( constructor) Reference results are not new objects o constructors are called for reference results. o Heap objects:. o Data objects:!

5 Default constructor: - Used to create an object without passing parameters to constructor. - Prototype syntax: Classname (void); - Sometimes the default constructor is optional: o If all instances are created by passing parameters to constructors. Default constructor is optional since it was never called. o If all instances are created without passing parameters to constructors. No constructors are ever called. Therefore, no constructors need to exist! Instantiated object was created not constructed. - Sometimes the default constructor is mandatory: o If instances are created both by passing parameters and without passing parameters to constructors. One you define the non-default constructor, you must define default one, too (as long as you are creating default objects).

6 Copy constructor: - Used to create an object from another object. - Prototype syntax: Classname (Classname &); - Implicitly called: o Creating an object as a parameter to a method. o Creating an object as a return result from a method. - Always optional: o Default behavior if missing: Member-wise copy is made. New object created is distinct from the original if the object is flat (no pointer data fields). Instantiated object was created not constructed.

7 Destructor rules: - Don t have a return type. - Only one can exist per class. o No parameters can be passed to it. - Used to destroy or clean up when an instance goes out of scope. - Prototype syntax: ~Classname (void); - Always optional: o Okay to not have one when the object is flat. o If pointer fields exist, then you ll need to deallocate memory with delete inside the body of destructor. Otherwise:. - Implicitly Called: o When a constructed object goes out of scope. RTS objects:. Heap objects:. Data objects:. - Can be explicitly called: o Code of destructor executed like any other method. Can be used to re-initialize an object. Rarely done. Destroying an array of heap objects: - Array brackets are needed to let the compiler know to call the destructor on all instances in the array. - Syntax: delete [] array_name;

CSE 12, Week Six, Lecture Two Discussion: Getting started on hw7 & hw8

CSE 12, Week Six, Lecture Two Discussion: Getting started on hw7 & hw8 Tree: What: - A container object - Composed of a TNodes o Each TNode holds - One root TNode pointer o The TNode in the Tree - Zero