Download to read offline
Uploaded byBlue Elephant Consulting
Intro to C++ - Class 2 - Objects & Classes
The document provides an introduction to software development using C++, detailing the history and evolution of the C programming language, the development of C++, and its features including object-oriented programming. It describes the typical development environment for a C++ program, the concepts of classes and objects, and emphasizes the benefits of object-oriented programming such as code reusability and productivity enhancements. Additionally, it includes a programming assignment to reinforce learning and future topics to be covered in subsequent classes.
Intro to C++ - Class 2 - Objects & Classes
- 1. An Introduction ToSoftware Development Using C++ Class #2: An Introduction To C++
- 2. What’s In AName? • The “C” programming language was developed by Dennis Ritchie at Bell Laboratories 1969-1973. He wanted to port the Unix operating system from a PDP-7 to a PDP-11 & he didn’t want to do it in assembly language. • Yes, the “B” language already existed. However, it sucked so he created “C” • C is available for most computers and is hardware independent. With careful design, it’s possible to write C programs that are portable to most computers. • The widespread use of C with various kinds of computers (sometimes called hardware platforms) unfortunately led to many variations. A standard version of C was needed. • The American National Standards Institute (ANSI) cooperated with the International Organization for Standardization (ISO) to standardize C worldwide; the joint standard document was published in 1990 and is referred to as ANSI/ISO 9899: 1990.
- 3. What Is C++? •C++, an extension of C, was developed by Bjarne Stroustrup in the early 1980s at Bell Laboratories. • C++ provides a number of features that “spruce up” the C language, but more importantly, it provides capabilities for object-oriented programming.
- 4. What Do YouHave To Do To “Learn” C++? Learn the C++ Language Learn how to use the classes and functions in the C++ Standard Library #1 #2
- 5. A Typical C++Program Development Environment Step #1: Write the program! // Text-printing program. #include <iostream> // allows program to output data to the screen // function main begins program execution int main() { std::cout << "Welcome to C++!n"; // display message return 0; // indicate that program ended successfully } // end function main
- 6. A Typical C++Program Development Environment Step #2: Preprocess the program // Text-printing program. #include <iostream> // allows program to output data to the screen // function main begins program execution int main() { std::cout << "Welcome to C++!n"; // display message return 0; // indicate that program ended successfully } // end function main iostream
- 7. A Typical C++Program Development Environment Step #3: Compile the C++ program 00000100 00010010 00010001 00100100 00000000 11111001 00000111 01010101
- 8. A Typical C++Program Development Environment Step #4: Link the C++ program 00000100 00010010 00010001 00100100 00000000 11111001 00000111 01010101 00000100 00010010 00010001 00100100 00000000 11111001 00000111 01010101 00000100 00010010 00010001 00100100 00000000 11111001 00000111 01010101 00000100 00010010 00010001 00100100 00000000 11111001 00000111 01010101
- 9. A Typical C++Program Development Environment Step #5: Load the C++ program 00000100 00010010 00010001 00100100 00000000 11111001 00000111 01010101 00000100 00010010 00010001 00100100 00000000 11111001 00000111 01010101 00000100 00010010 00010001 00100100 00000000 11111001 00000111 01010101 00000100 00010010 00010001 00100100 00000000 11111001 00000111 01010101
- 10. What’s Up WithThis Object Orientated Stuff? Procedural Languages One long piece of code where data and logic are all mixed in together. 1 # 2 # Sample program that demonstrates the print function. 3 # 4 5 # Prints 7 6 print(3 + 4) 7 8 # Prints “Hello World!” in two lines. 9 print("Hello") 10 print("World!") 11 12 # Prints multiple values with a single print function call. 13 print("My favorite numbers are", 3 + 4, "and", 3 + 10) 14 15 # Prints three lines of text with a blank line. 16 print("Goodbye") 17 print() 18 print("Hope to see you again")
- 11. What’s Up WithThis Object Orientated Stuff? • Each object represents a different part of the application. • Each object contains it’s own data & it’s own logic. • The objects communicate between themselves. • Objects are designed to represent how you talk and think about the actual problem. • Objects are meant to make thinking about your program easier. • Object orientation is just an idea that is supported by C++
- 12. I Know HowTo Program, Why Bother With This C++ Stuff? • Why is so much attention today focused on object-oriented programming in general and C++ in particular? ANSWER: Object-oriented programming enables the programmer to build reusable software components that model items in the real world. Building software quickly, correctly, and economically has been an elusive goal in the software industry. The modular, object-oriented design and implementation approach has been found to increase productivity 10 to 100 times over conventional programming languages while reducing development time, errors, and cost. C++ is extremely popular because it is a superset of the widely used C programming language. Programmers already familiar with C have an easier time learning C++. Image Credit: www.dreamstime.com
- 13. What are “Objects”? Objects(both software and real) have two ways that they can be represented: A. Attributes B. Behaviors
- 14. What are “Objects”? Thegas pedal hides from the driver the complex mechanisms that actually make the car go faster, just as the brake pedal hides the mechanisms that slow the car, and the steering wheel “hides” the mechanisms that turn the car. This enables people with little or no knowledge of how engines, braking and steering mechanisms work to drive a car easily. Objects work the same way – they hide your code from other developers so that they don’t have to know HOW you did something, just what your code DOES.
- 15. Member Functions andClasses Performing a task in a program requires a member function, which houses the program statements that actually perform its task. The member function hides these statements from its user, just as the accelerator pedal of a car hides from the driver the mechanisms of making the car go faster. In C++, we create a program unit called a class to house the set of member functions that perform the class’s tasks. For example, a class that represents a bank account might contain one member function to deposit money to an account, another to withdraw money from an account and a third to inquire what the account’s current balance is. A class is similar in concept to a car’s engineering drawings, which house the design of an accelerator pedal, steering wheel, and so on.
- 16. What Is AClass? • It’s a blueprint, the definition, the description. • It is not the thing itself! Image Credit: www.chickslovethecar.com
- 17. Example Classes Restaurant ReviewUser Textbox Button Window Date Timezone Daylight Savings
- 18. Instantiation You must buildan object of a class before a program can perform the tasks that the class’s member functions define. The process of doing this is called instantiation. An object is then referred to as an instance of its class.
- 19. Object • The objectis created from the class • One class can create multiple objects Image Credit: http://8z4.net/images/blueprint-/5.html
- 20. Reuse You can reusea class many times to build many objects. Reuse of existing classes when building new classes and programs saves time and effort. Reuse also helps you build more reliable and effective systems, because existing classes and components often have gone through extensive testing, debugging and performance tuning.
- 21. Messages and Member FunctionCalls When you drive a car, pressing its gas pedal sends a message to the car to perform a task—that is, to go faster. Similarly, you send messages to an object. Each message is implemented as a member function call that tells a member function of the object to perform its task. For example, a program might call a particular bank account object’s deposit member function to increase the account’s balance.
- 22. Attributes and DataMembers A car, besides having capabilities to accomplish tasks, also has attributes, such as its color, its number of doors, the amount of gas in its tank, its current speed and its record of total miles driven (i.e., its odometer reading). As you drive an actual car, these attributes are carried along with the car. Every car maintains its own attributes. For example, each car knows how much gas is in its own gas tank, but not how much is in the tanks of other cars. An object, similarly, has attributes that it carries along as it’s used in a program. These attributes are specified as part of the object’s class. For example, a bank account object has a balance attribute that represents the amount of money in the account. Each bank account object knows the balance in the account it represents, but not the balances of the other accounts in the bank. Attributes are specified by the class’s data members.
- 23. What Does AClass Define? Attributes Name Height Weight Gender Age Behavior Walk Run Jump Speak Sleep Let’s say that our class is designed to describe a person…
- 24. Encapsulation Classes encapsulate (i.e.,wrap) attributes and member functions into objects—an object’s attributes and member functions are intimately related. Objects may communicate with one another, but they’re normally not allowed to know how other objects are implemented—implementation details are hidden within the objects themselves. This information hiding, as we’ll see, is crucial to good software engineering.
- 25.
- 26. Inheritance A new classof objects can be created quickly and conveniently by inheritance—the new class absorbs the characteristics of an existing class, possibly customizing them and adding unique characteristics of its own. In our car analogy, an object of class “convertible” certainly is an object of the more general class “automobile,” but more specifically, the roof can be raised or lowered.
- 27. Object-Oriented Analysis and Design(OOAD) To create the best solutions, you should follow a detailed analysis process for determining your project’s requirements (i.e., defining what the system is supposed to do) and developing a design that satisfies them (i.e., deciding how the system should do it). Ideally, you’d go through this process and carefully review the design (and have your design reviewed by other software professionals) before writing any code. If this process involves analyzing and designing your system from an object-oriented point of view, it’s called an object-oriented analysis and design (OOAD) process. Languages like C++ are object oriented. Programming in such a language, called object-oriented programming (OOP), allows you to implement an object-oriented design as a working system.
- 28. In-Class Fun: Running AC++ Program What you are going to be doing: 1. Locate and download the working C++ program that I’ve given you 2. Start up the C++ compiler 3. Compile the code 4. Run the code 5. Quit the compiler
- 29. What We CoveredToday 1. Where did C / C++ come from? 2. What happens when you compile a C++ program? 3. What are “objects”? 4. Compiling and running your very 1st C++ program. Image Credit: http://www.tswdj.com/blog/2011/05/17/the-grooms-checklist/
- 30. What We’ll BeCovering Next Time 1. Taking apart our first C++ program 2. Displaying data on the screen 3. Output streams Image Credit: http://merchantblog.thefind.com/2011/01/merchant-newsletter/resolve-to-take-advantage-of-these-5-e-commerce-trends/attachment/crystal-ball-fullsize/
- 31. An Introduction ToSoftware Development Using C++ Class #2: Introduction To The In-Class Programming Assignment
- 32. Today’s In-Class C++ ProgrammingAssignment • Write a C++ program that will ask you to enter your age. It will then print out the following statement: Hello, you have been alive for <x> days. Assume every year has 365 days.
- 33. Answer To Today’sChallenge // In-Class Exercise #1- Days Alive #include <iostream> using std::cout; using std::endl; using std::cin; int main() { int age; cout << "Please Enter Your Age "; cin >> age; cout << "Hello, you have been alive for " << age * 365 << " days."; return(0); } Image Credit: www.clipartpanda.com
- 34. What’s In YourC++Toolbox? cout cin
- 35. What We CoveredToday 1. Got our first in-class programming assignment. 2. Found out how many days we’ve been alive. 3. Found out how many days we’ll probably live Image Credit: http://www.tswdj.com/blog/2011/05/17/the-grooms-checklist/
- 36. What We’ll BeCovering Next Time 1. How to find out which number is larger? Image Credit: http://merchantblog.thefind.com/2011/01/merchant-newsletter/resolve-to-take-advantage-of-these-5-e-commerce-trends/attachment/crystal-ball-fullsize/
Editor's Notes
- #2 New name for the class I know what this means Technical professionals are who get hired This means much more than just having a narrow vertical knowledge of some subject area. It means that you know how to produce an outcome that I value. I’m willing to pay you to do that.
- #32 New name for the class I know what this means Technical professionals are who get hired This means much more than just having a narrow vertical knowledge of some subject area. It means that you know how to produce an outcome that I value. I’m willing to pay you to do that.