tailieunhanh - Object Oriented Programming (20)

CSC241: Object Oriented Programming. Lecture No 22. 1 Previous Lecture.•. Friend function. – example program: Distance class. – Friend function for functional notation.•. Friend classes.•. static functions.•. Assignment operator and copy initialization. 2 Today’s Lecture.•. Example program. – Copy initialization. – Assignment operator overloaded.•. Memory efficient string class.•. Dynamic Type Information. 3 The Copy Constructor.•. Distance d2 = d1;. d2 d1. feet 7 feet 7. inche inche. . s s•. It is similar to what assignment operator (d2 =. d1) does.•. The difference is that copy initialization also. creates a new object 4 Example program – assignment alpha { copy constructor. void display(). private: { cout << data; }. int data; void operator = (alpha&. public: a) {. alpha() { } data = ;. alpha(int d) cout << “\nAssignment. { data = d; } operator invoked”;. alpha(alpha& a) { }. data = ; };. cout << “\nCopy a2 = a1;. alpha a3(a1);. constructor. invoked”; Program Output. } Assignment operator. invoked. Copy constructor invoked. 5 When Copy constructor is invoked1. Copy constructor may be invoked when an. object is defined. . alpha a3 = a2; or alpha a3(a2);.2. when arguments are passed by value to. functions void func(alpha a) { . . . }Alpha a =. called by the statement a1;. func(a1);.5. when values are returned from functions. 6 Why Not alpha(alpha a) Constructor?.•. Do we need to use a reference in the argument. to the copy constructor? alpha(alpha &a).•. Could we pass by value instead? alpha(alpha a). No, the compiler complains that it is out of. memory if we try to compile.•. Why?. •. Because when an argument is passed by. value, a copy of it is constructed What makes. the copy?. •. The copy constructor. But this is the copy 7 A Memory-Efficient String Class.•. Defects with the String Class S1. This is a long. – String object contains an array of char string in. memory. – s2 = s1;. S2. – problem with this is that the same string This is a long. now exists in two (or more) places in string in. memory. memory.•. An efficient approach S1 S2. • String object contain its own char*. • s2 = s1; This is a long. string in. • This is efficient, since only a single copy memory. of the string itself needs to be stored in 8 Problem with efficient approach.•. If we use this system we need to be careful. when we destroy a String object.•. Consider a situation in which several objects are. point to same string. S1 S2 S3.•. If one string objec

• Sáng kiến kinh nghiệm
• Object Oriented Programming
• Object Initializatio
• Usage Acquaint
• Data initialization
• Object usage
• Object declaration
• Programming languages
• Lecture Object oriented programming
• Lập trình hướng đối tượng
• Object oriented programming with Java
• Object oriented programming in C++
• Software object
• Bài giảng Lập trình hướng đối tượng
• Architectural models
• Mechanical models
• Tangible object
• Lesson Object
• Unified inheritance hierarchy
• Access through Object reference
• Unique Type object
• Simple type string conversion
• Automatic use of ToString
• Bài giảng Photoshop
• Làm việc với Smart Object
• Cách sử dụng Filter
• Cách mở tấm hình dưới dạng Smart Object
• Chỉnh sửa đối tượng Smart Object
• Làm việc với các filter
• Object Oriented Data Modeling
• Data Modeling
• UML Language
• Object Oriented Modeling
• Object Modeling Example
• Tranform Class Diagram to Relational Database Schema
• Programming language
• Java programming language
• Sample object returning method
• Overloaded methods
• JFileChooser object
• Primitive data types
• String Tokenizer object
• Abstract classes
• Java program
• Object serialization
• Data hierarchy
• Sequential access text files
• Object oriented software engineering
• Software engineering
• Practical software development
• Object orientation
• Modeling with classes
• Object diagrams
• Inheritance hierarchies
• Variable declarations
• Object detection
• Recognition in digital images
• Object detection and tracking
• Object recognition
• Template based recognition
• Object Oriented Programing
• Lecture Object Oriented Programing
• Direct superclass
• Indirect superclass
• Effect polymorphism
• Demonstrating polymorphic behavior
• Class file
• Instance data values
• Class data value
• Software development
• C++ programming