Introduction to C++

Introduction to C++

Introduction to Computers   Overview A computer is a machine that receives instructions and produces a result after performing an appropriate assignment. Since it is a machine, it expects good and precise directives in order to do something. The end result depends on various factors ranging from the particular capabilities of the machine, the instructions it received, and the expected result. As a machine, the computer cannot figure out what you want. The computer doesn't think and therefore doesn't make mistakes. Computer programmingis the art of writing instructions (programs) that ask the computer to do something and give a result. A computer receives instructions in many different forms, four of which are particularly important. The first instructions are given by the manufacturers of various hardware parts such as the microprocessor, the motherboard, the floppy and the CD-ROM drives, etc. These parts are usually made by different companies, setting different and various goals that their particular part can perform. The instructions given to the microprocessor, for example, tell it how to perform calculations, at what speed, and under which circumstances. The instructions given to the motherboard tell it to behave like a city where people and cars can move from one part of the town to another, back and forth, for various reasons; this allows information to flow from one part of the city, I mean one section of the computer, to another. Once the instructions given to the hardware parts are known, software engineers use that information to give the second sets of instructions to the computer. These instructions, known as an operating system, are usually written by one company. These second instructions tell the computer how to coordinate its different components so the result will be a combination of different effects. This time, the computer is instructed about where the pieces of information it receives are coming from, what to do with them, then where to send the result. This time also the operating system designers impose a lot of behaviors to the computer as a machine. Again this time, some computer languages are developed so that programmers can write applications as the third set of instructions. It is like developing languages that people in a city can use to talk to each other. Consider that from now on (once the OS is developed), people get into the habit of doing things according to their particular culture or taste, speaking different languages that their neighbor doesn't understand... Luckily, the computer, I should say the OS, understands all these languages (I can't guaranty that). Some of the operating systems on the market are: Microsoft Windows 3.X, Corel Linux, IBM OS\2, Microsoft Windows 9X, Apple OS 10, Red Hat Linux, Microsoft Windows Millennium, BeOS, Caldera Linux, Microsoft Windows 2000 etc. A particular OS (for example Microsoft Windows 98) depending on a particular processor (for example Intel Pentium) is sometimes referred to as a platform. Some of the computer languages running on Microsoft Windows operating systems are C++, Pascal, Basic, and their variants.

C++ Tutorial - Introduction - WHAT IS C++ THE ORIGIN OF C++ The C programming language was developed at AT&T for the purpose of writing the operating system for the PDP-11 series of computers which ultimately became the UNIX operating system. C was developed with the primary goal of operating efficiency. Bjarne Stroustrup, also of AT&T, developed C++ in order to add object oriented constructs to the C language. Because object oriented technology was new at the time and all existing implementations of object oriented languages were very slow and inefficient, the primary goal of C++ was to maintain the efficiency of C. C++ can be viewed as a traditional procedural language with some additional constructs. Beginning with C, some constructs are added for object oriented programming and some for improved procedural syntax. A well written C++ program will reflect elements of both object oriented programming style and classic procedural programming. C++ is actually an extendible language since we can define new types in such a way that they act just like the predefined types which are part of the standard language. C++ is designed for large scale software development. HOW TO GET STARTED IN C++ The C programming language was originally defined by the classic text authored by Kernigan and Ritchie, "The C Programming language", and was the standard used by all C programmers until a few years ago. The ANSI standard for C was finally approved in December of 1989 and has become the official standard for programming in C. The ANSI-C standard adds many things to the language which were not a part of the Kernigan and Ritchie definition, and changes a few. The two definitions are not absolutely compatible and some experienced C programmers may not have studied the newer constructs added to the language by the ANSI-C standard. This tutorial will assume a thorough knowledge of the C programming language and little time will be spent on the fundamental aspects of the language. However, as a aid to those programmers that have learned the dialect of C as defined by Kernigan & Ritchie, some sections will be devoted to explaining the newer additions included in the ANSI-C standard. As the ANSI-C standard was in development, many of the newer constructs from C++ were included as parts of C itself, so even though C++ is a derivation and extension of C, it would be fair to say that ANSI-C has some of its roots in C++. An example is prototyping which was developed for C++ and later added to C. The best way to learn C++ is by using it. Almost any valid C program is also a valid C++ program and, in fact, the addition of about 12 keywords is the only reason that some C programs will not compile and execute as a C++ program. There are a few other subtle differences, but we will save the discussion of them until later. Since this is true, the best way to learn C++ is to simply add to your present knowledge and use a few new constructs as you need them for each new project. It would be a tremendous mistake to try to use all of the new constructs in your first C++ program. You would probably end up with an incomprehensive mixture of code that would be more inefficient than the same program written purely in C. It would be far better to add a few new constructs to your toolkit occasionally, and use them as needed while you gain experience with their use. As an illustration of the portability of C to C++, all of the example programs included in the Coronado Enterprises C tutorial compiled and executed correctly when compiled as C++ programs with no changes. Note that this was version 2.6 which was released in 1994. The updates in the C++ compilers since then may have made this statement false for newer versions. None of the C++ programs will compile and execute correctly with any C compiler however, if for no other reason than the use of the new style of C++ comments. HOW TO USE THIS TUTORIAL This tutorial is best used while sitting in front of your computer. It is designed to help you gain experience with your own C++ compiler in addition to teaching you the proper use of C++. Display an example program on the monitor, using whatever text editor you usually use, and read the accompanying text which will describe each new construct introduced in the example program. After you study the program, and understand the new constructs, compile and execute the program with your C++ compiler. After you successfully compile and execute the example program, introduce a few errors into the program to see what kind of error messages are issued. If you have done much programming, you will not be surprised if your compiler gives you an error message that seems to have nothing to do with the error introduced. This is because error message analysis is a very difficult problem with any modern programming language. The most important result of these error introduction exercises is the experience you will gain using your compiler and understanding its nuances. You should then attempt to extend the program using the techniques introduced with the program to gain experience. The way this tutorial is written, you will not find it necessary to compile and execute every program. At the end of each example program, listed in comments, you will find the result of execution of that program. Some of the constructs are simple and easy for you to understand, so you may choose to ignore compilation and execution of that example program, depending upon the result of execution to give you the output. Some students have used these results of execution to study several chapters of this tutorial on an airplane by referring to a hardcopy of the example programs. In the text of this tutorial, keywords, variable names, and function names will be written in bold type as an aid when you are studying the example programs. DIFFERENT C++ IMPLEMENTATIONS There are primarily two standards for naming C++ files, one using the extension CPP and the other using the extension CXX. All files in this tutorial use the CPP extension for naming files. If your compiler requires the CXX extension it will be up to you to rename the files. When C++ was in its infancy, header files generally used the extension .HPP, but there is a definite trend to use .H for all header files. For that reason all header files in this tutorial will use that convention. Even though we have tried to use the most generic form of all constructs, it is possible that some constructs will not actually compile and run with some C++ compilers. As we find new implementations of C++, and acquire copies of them, we will compile and execute all files in an attempt to make all example programs as universal as possible. A committee is currently meeting to produce an ANSI-C++ standard, but the standard is not expected to be available for general use until 1998 at the earliest. Until then we must expect a few changes to the language. In fact, there have been many changes in the last two years as compiler writers are trying to catch up with the language changes. PROGRAMMING EXERCISES There are programming exercises given at the end of each chapter to enable you to try a few of the constructs given in the chapter. These are for your benefit and you will benefit greatly if you attempt to solve each programming problem. If you merely read this entire tutorial, you will have a good working knowledge of C++, but you will only become a C++ programmer if you write C++ programs. The programming exercises are given as suggestions to get you started programming. An answer for each programming exercise is given in the cppans.zip file available for download in the same manner as the source files. The answers are all given in compilable C++ source files named in the format CHnn_m.CPP, where nn is the chapter number and m is the exercise number. If more than one answer is required, an A, B, or C, is included following the exercise number. RECOMMENDED ADDITIONAL READING Margaret Ellis & Bjarne Stroustrup. "The Annotated C++ Reference Manual". Addison-Wesley, 1990. This is the base document for the ANSI-C++ standard. Even though it is the definitive book on C++, it would be difficult for a beginner to learn the language from this book alone. Scott Meyers. "Effective C++, 50 Specific Ways to Improve Your Programs and Designs". Addison-Wesley, 1992. This book is excellent for the advanced C++ programmer, but it is definitely not for the beginner. Scott Meyers. "More Effective C++, 35 New Ways to Improve Your Programs and Designs". Addison-Wesley, 1996. This book is excellent for the advanced C++ programmer, following completion of the above reference. Note that the C++ culture is in rapid change and by the time you read this, there will be additional well written texts available as aids to your learning the syntax and proper use of the C++ programming language.