C++ ReviewC++ Review - Washington Stateananth/CptS223/Lectures/C++-review.pdf · Purpose of Review...

transcript

C++ ReviewC++ Review

11Cpt S 223. School of EECS, WSU

Purpose of Review

Review some basic C++ Familiarize us with Weiss’s style Familiarize us with Weiss s style Some good coding practices

d f f l f Introduce specific constructs useful for implementing data structures

STL overviewNote: Not all slides shown in PPT;

Refer to the PDF version of slides for thatCpt S 223. School of EECS, WSU

The Class defines the data structure and the operations that access and pmanipulate it Member data Member functions or methods

Encapsulation = data + methods Information hiding

Public vs. private vs. protected

Comment

Constructor

Encapsul

InformationHiding

Separation of Interface and Implementation

Interface (.h) file Defines class and its member data and Defines class and its member data and

functions

Implementation ( cc or cpp) file Implementation (.cc or .cpp) file Provides implementations of member

functionsfunctions

Extra Syntax

Default parameters Initializer list Initializer list Explicit constructor

b f Constant member function Accessor methods Mutator methods

Default ExplicitParameters

pConstructor

InitializerLi tAccessor ListAccessor

Mutator

IntCell obj;obj = 37;

Mutator

PreprocessorDirectives

IntCell class interface in file IntCell.h.

Cpt S 223. School of EECS, WSU

PreprocessorDirective

ScopinggOperator

ClassName::member

10IntCell class implementation in file IntCell.cpp.Cpt S 223. School of EECS, WSU

PreprocessorDirectivesDirectives

Default class

Program using IntCell class in file TestIntCell.cpp.

C++ Details

Pointers Parameter passing Parameter passing Return passing

f bl Reference variables Destructor, copy constructor, operator=

Pointers

Address-of operator &

IntCell icObj;IntCell *m = & icObj;

No garbage collection in C++

Parameter Passing

Call by value Small objects not altered by function Small objects not altered by function

Call by constant referenceLarge objects not altered by function Large objects not altered by function

Call by reference Objects altered by function

double avg (const vector<int> & arr int n bool & errorFlag);

double avg (const vector<int> & arr, int n, bool & errorFlag);

What’s wrong with this code? Return passing

Reference Variables

As seen, can be used for parameter passingpassing

Also used as synonyms for the objects they referencethey reference Avoid cost of copying

string x = findMax (a);cout << x << endl;

const string & x = findMax (a);cout << x << endl;

Destructor

Default definitions for all classes Destructor Destructor

Called when object goes out of scope or subject to a delete

By default, calls destructor on all data membersMi ht t t d l bj t t d Might want to delete objects created using new

Might want to close any opened files

Might want to close any opened files.

Copy Constructor Copy constructor

Declaration during initialization IntCell B = C; IntCell B = C; IntCell B (C);

Object passed using call by value (instead of by &or const & )or const & )

Object returned by value (instead of by & or const & )

Simple assignment for all members with Simple assignment for all members with primitive data types (e.g., int, double, …)

Calls copy constructors on all member objects

operator=

Copy assignment operator: operator= Called when objects on both sides of Called when objects on both sides of

assignment already constructed E.g., IntCell B(0);g ,

IntCell C(1);B = C;

By default, operator= called on each data member of objects

data member of objects

Default destructor, copy constructor and operator= for IntCell

Problems with Defaults

O t t?

Output?

Fixing the Defaults

Templates

Designing type-independent data structures and algorithmsstructures and algorithms

Function templatesClass templates Class templates

Function Templates

Class Templates

C++ Standard Template Library: Basics

SGI’s web reference:SGI s web reference:http://www.sgi.com/tech/stl/

Key concepts

Containers Iterators Iterators

Example Problem

Find the maximum in an (i) linked list of integers (i) linked list of integers (ii) array of integers

Coding using STL

Linked List Array

*curr; *curr;

Do you see the advantage of using iterators in the above example?

List of containers

STL container: Data structure that it implements:

vector Arrayvector Array

list Doubly-linked list

slist Singly-linked listg y

queue FIFO structure

stack LIFO structure

deque Array-like structure with efficient insertion & removal at both ends

set Set of unique elements

API for the containersFunction: Purpose:push_front Inserts elements before the first (not available for vector)

pop front Removes the first element (not available for vector)pop_front Removes the first element (not available for vector)

push_back Appends element at the end

pop_back Removes element from the end

empty Boolean indicating if the container is empty p y oo a d a g o a s p y

size Returns number of elements

insert Insert an element in a position

erase Removes an element at a position

clear Removes all elements

resize Resizes the container

front Returns a reference to the first element

Back Returns a reference to the last element

[] Subscripting access without bounds checking

at Subscripting access with bounds checkingCpt S 223. School of EECS, WSU

Summary

Basic C++ Templates Templates Tools for easing the design of type-

independent data structures andindependent data structures and algorithms

Please refer to the PDF slides to see all slides. S hidd i th PPT (f th k f

Some are hidden in the PPT (for the sake of presentation)

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