Introduction

Software: 

       A computer program is an example of computer software. Software makes a computer a truly universal machine transforming it into the proper tool for the task. One can refer to a program as a piece of software as if it were a tangible object, but software is actually intangible. It is stored on a medium. A hard drive, a CD, a DVD, and a USB pen drive are all examples of media upon which software can reside. The CD is not the software; the software is a pattern on the CD. In order to be used, software must be stored in the computer’s memory. Typically, computer programs are loaded into memory from a medium like the computer’s hard disk. An electromagnetic pattern representing the program is stored on the computer’s hard drive. This pattern of electronic symbols must be transferred to the computer’s memory before the program can be executed. The program may have been installed on the hard disk from a CD or from the Internet. In any case, the essence that was transferred from medium to medium was a pattern of electronic symbols that direct the work of the computer system. These patterns of electronic symbols are best represented as a sequence of zeroes and ones, digits from the binary (base 2) number system. An example of a binary program sequence is 1000101101100001 To the underlying computer hardware, specifically the processor, a zero here and three ones there might mean that certain electrical signals should be sent to the graphics device so that it makes a certain part of the display screen red. Unfortunately, only a minuscule number of people in the world would be able to produce, by hand, the complete sequence of zeroes and ones that represent the program Microsoft Word for an Intel-based computer running the Windows 8 operating system. Further, almost none of those who could produce the binary sequence would claim to enjoy the task. The Word program for older Mac OS X computers using a PowerPC processor works similarly to the Windows version and indeed is produced by the same company, but the program is expressed in a completely different sequence of zeroes and ones! The Intel Core i7 processor in the Windows machine accepts completely different binary language than the PowerPC processor in the Mac. We say the processors have their own machine language.
Programmers have a variety of tools available to enhance the software development process. Some common tools include

• Editors:        An editor allows the user to enter the program source code and save it to files. Most programming editors increase programmer productivity by using colors to highlight language features. The syntax of a language refers to the way pieces of the language are arranged to make well-formed sentences. To illustrate, the sentence 

·        The tall boy runs quickly to the door.

Uses proper English syntax. By comparison, the sentence 

·        Boy the tall runs door to quickly the.

Is not correct syntactically. It uses the same words as the original sentence, but their arrangement does not follow the rules of English. Similarly, programmers must follow strict syntax rules to create well-formed computer programs. Only well-formed programs are acceptable and can be compiled and executed. 
                      

• Compilers:         

   A compiler translates the source code to target code. The target code may be the machine language for a particular platform or embedded device. The target code could be another source language; for example, the earliest C++ compiler translated C++ into C, another higher-level language. A C compiler to produce an executable program then processed the resulting C code. C++compilers today translate C++ directly into machine language. The complete set of build tools for C++ includes a preprocessor, compiler, and linker: – Preprocessor—adds to or modifies the contents of the source file before the compiler begins processing the code. We use the services of the preprocessor mainly to #include information about library routines our programs use.

Compiler—translates C++ source code to machine code.

 Linker—combines the compiler-generated machine code with pre-compiled library code or compiled code from other sources to make a complete executable program. Most compiled++ code is incapable of running by itself and needs some additional machine code to make complete executable program. The missing machine code has been precompiled and stored in repository of code called a library. A program called a linker combines the programmer’s compiled code and the library code to make a complete program. We generally do not think about the preprocessor, compiler, and linker working as three separate programs (although they do); the tools we use make it appear as only one process is taking place: translating our source code to an executable program.

• Debuggers:       

  A debugger allows a programmer to more easily trace a program’s execution in order to locate and correct errors in the program’s implementation. With a debugger, a developer can simultaneously run a program and see which line in the source code is responsible for the program’s current actions. The programmer can watch the values of variables and other program elements to see if their values change as expected. Debuggers are valuable for locating errors (also called bugs) and repairing programs that contain errors. 

• Profilers:       

A profiler collects statistics about a program’s execution allowing developers to tune appropriate parts of the program to improve its overall performance. A profiler indicates how many times a portion of a program is executed during a particular run, and how long that portion takes to execute. Profilers also can be used for testing purposes to ensure all the code in a program is actually being used somewhere during testing. This is known as coverage. It is common for software to fail after its release because users exercise some part of the program that was not executed anytime during testing. The main purpose of profiling is to find the parts of a program that can be improved to make the program run faster.

What is programming anyway?

Programming means telling a computer what to do.

"Do this, then do that, than take the two results, mix them up this way, and repeat until you get a pizza out of it…". It's a bit like cooking.

So, what are the basic operations that a computer can perform?

Of course, a computer can do many things, but at a very basic level, programs consists of the following types of instructions:

1.     Input: get data from the keyboard or from some file or other device.

2.     Output: showing the result on the interface.

3.     Math: perform some simple calculation, like addition and multiplication.

4.     Conditional execution: check some condition and execute one sequence of statements.

5.     Repetition: repeat some sequence of operations, usually with some variation

What is C++ language?

    C++ is an object oriented programming (OOP) language, developed by Bjarne Stroustrup, and is an extension of C language. It is therefore possible to code C++ in a "C style" or "object-oriented style.

Before the initial standardization in 1998, C++ was developed by Bjarne Stroustrup at Bell Labs since 1979, as an extension of the C language as he wanted an efficient and flexible language similar to C, which also provided high-level features for program organization.

It is pronounced "C-Plus-Plus." 

Learning Programming with C++

              Bjarne Stroustrup of AT&T Bell Labs created C++ in the mid-1980s. C++ is an extension of the programming language C, a product of AT&T Bell Labs from the early 1970s. C was developed to write the Unix operating system, and C is widely used for systems-level software and embedded systems development C++ initially provided object-oriented programming features (see Chapter 13 and Chapter 14) and later added generic programming capabilities. C++’s close relationship to C allows C++ programs to utilize large collection of code developed in C.C++ is widely used in industry for commercial software development. It is an industrial strength programming language used for developing complex systems in business, science, and engineering. Examples of software written in C++ include Microsoft Windows 8, Microsoft Office, Mac OS X, and Adobe Creative Suite.

• #include <iostream> 

         This line is a preprocessing directive. All preprocessing directives within C++ source code begin with # symbol. This one directs the preprocessor to add some predefined source code to our existing source code before the compiler begins to process it. This process is done automatically and is invisible to us. Here we want to use some parts of the iostream library, a collection precompiled C++ code that C++programs (like ours) can use. The iostream library contains routines that handle input and output(I/O) that include functions such as printing to the display, getting user input from the keyboard, and dealing with files. Two items used in Listing 2.1 (simple.cpp), cout and endl, are not part of the C++ language itself. These items, along with many other things related to input and output, were developed in C++, compiled, and stored in the iostream library. The compiler needs to be aware of these iostreamitems so it can compile our program. The #include directive specifies a file, called a header, thatcontains the specifications for the library code. The compiler checks how we use cout and end within our code against the specifications in the <iostream> header to ensure that we are using the library code correctly. Most of the programs we write use this #include <iostream> directive, and some programs we will write in the future will #include other headers as well

. • using namespace STD;  

            The two items our program needs to display a message on the screen, cout and endl, have longer names: std::cout and std::endl. This using namespace STD directive allows us to omit the STD: prefix and use their shorter names. This directive is optional, but if we omit it, we must use the longer names. Listing 2.2 (simple2.cpp) shows how the longer names are used. The name STD stands for “standard and the using namespace std line indicates that some of the names we use in our program are part of the so-called “standard namespace.”

• Int main () {

This specifies the real beginning of our program. Here we are declaring a function named main. All++ programs must contain this function to be executable. Details about the meaning of int and the parentheses will appear in later chapters. The opening curly brace at the end of the line marks the beginning of the body of a function. The body of a function contains the statements the function is to execute.

• Cout << "This is a simple C++ program!"<< endl;

The body of our main function contains only one statement. This statement directs the executing program to print the message this is a simple C++ program! On the screen. A statement is the fundamental unit of execution in a C++ program. Functions contain statements that the compiler translates into executable machine language instructions. C++ has a variety of different kinds of statements, and the chapters that follow explore these various kinds of statements. All statements inch++ end with a semicolon (;). A more detailed explanation of this statement appears below

 • }

         The closing curly brace marks the end of the body of a function. Both the open curly brace and close curly brace are required for every function definition.