cpp 1 corrected)

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Computers are electronic information-processing machines. Data and programs in

these machines are saved, moved, and transformed in the form of electrical voltages.

These electrical voltages can be interpreted as a zeros and ones. The zeros andones can be aggregated and interpreted as words, numbers, images, sounds, and

so on.

Long ago, informationbe it data or programscould be entered into the computer by

manipulating switches on the front of the machine. Today, there are better methods.

Computer programming languages convert text into the requisite binary instructions.

If your computer could understand English, you would not have to learn a programming

language. But because it does not understand English, you must learn to write instructions

in a language your computer recognizes.


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Early computers were programmed in machine language. To see how instructions are written

in machine language, suppose you want to use the equation:

wages = rate * hours

to calculate weekly wages.

Further, suppose that the binary code 100100 stands for load, 100110 stands for

multiplication, and 100010 stands for store. In machine language, you might need the

following sequence of instructions to calculate weekly wages:

100100 010001

100110 010010

100010 010011

To represent the weekly wages equation in machine language, the programmer had to

remember the machine language codes for various operations. Also, to manipulate data, the

programmer had to remember the locations of the data in the main memory. This need to

remember specific codes made programming not only very difficult, but also error-prone.


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The 1960s gave birth to structured programming. This is the method of

programming supported by languages such as C. With structured languages, it

was, for the first time, possible to write moderately complex programs fairly easily.

Dividing a problem into smaller subproblems is called structured design. Each

subproblem is then analyzed, and a solution is obtained to solve the subproblem.

The solutions to all of the subproblems are then combined to solve the overall

problem. This process of implementing a structured design is called structured

programming. The structured-design approach is also known as top-down design,

bottom-up design, stepwise refinement, and modular programming.

However, even with structured programming methods, once a project reaches a

certain size, its complexity exceeds what a programmer can manage. By the late

1970s, many projects were near or at this point. To solve this problem, a new way

to program began to emerge.

This method is called object-oriented programming (OOP for short). Using OOP, a

programmer could handle larger programs. The trouble was that C did not support

object-oriented programming. The desire for an object-oriented version of C

ultimately led to the creation of C++.


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In response to the need to manage greater complexity, C++ was born. It was invented

by Bjarne Stroustrup in 1979 at Bell Laboratories in Murray Hill, New Jersey. He initially

called the new language C with Classes. However, in 1983 the name was changed

to C++.

C++ contains the entire C language. As stated earlier, C is the foundation upon which C++ is

built. C++ includes all of Cs features, attributes, and benefits. It also adheres to Cs

philosophy that the programmer, not the language, is in charge. At this point, it is critical to

understand that the invention of C++ was not an attempt to create a new programming

language. Instead, it was an enhancement to an already highly successful language.


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Most of the additions that Stroustrup made to C were designed to support object-oriented

programming. In essence, C++ is the object-oriented version of C. By building upon the

foundation of C, Stroustrup provided a smooth migration path to OOP. Instead of having to

learn an entirely new language, a C programmer needed to learn only a few new features toreap the benefits of the object-oriented methodology. But C is not the only language that

influenced C++.

Stroustrup states that some of its object-oriented features were inspired by another object-

oriented language called Simula67. Therefore, C++ represents the blending of two powerful

programming methods.

When creating C++, Stroustrup knew that it was important to maintain the original spirit of C,

including its efficiency, flexibility, and philosophy, while at the same time adding support for

object-oriented programming. Happily, his goal was accomplished.

C++ still provides the programmer with the freedom and control of C, coupled with the powerof objects.


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What Is Object-Oriented Programming?

Since object-oriented programming was fundamental to the development of C++, it

is important to define precisely what object-oriented programming is.

Object-oriented programming has taken the best ideas of structured programming and has

combined them with several powerful concepts that allow you to organize your programs

more effectively.

In general, when programming in an object-oriented fashion, you decompose a problem

into its constituent parts.

Each component becomes a self-contained object that contains its own instructions and

data related to that object. Through this process, complexity is reduced and you can

manage larger programs.

All object-oriented programming languages have three things in common: encapsulation,

polymorphism, and inheritance.


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Encapsulation

As you probably know, all programs are composed of two fundamental elements:

program statements (code) and data. Code is that part of a program that performs actions, and

data is the information affected by those actions.

Encapsulation is a programming mechanism that binds together code and the data it

manipulates, and that keeps both safe from outside interference and misuse.

In an object-oriented language, code and data may be bound together in such a way that a self-

contained black box is created. Within the box are all necessary data andcode. When code and

data are linked together in this fashion, an object is created.

In other words, an object is the device that supports encapsulation. Within an object, the code,

data, or both may be private to that object or public.

Private code or data is known to, and accessible only by, another part of the object. That is,

private code or data may not be accessed by a piece of the program that exists outside theobject. When code or data ispublic, other parts of your program may access it, even though it is

defined within an object. Typically, the public parts of an object are used to provide a controlled

interface to the private elements of the object.


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Polymorphism

Polymorphism (from the Greek, meaning many forms) is the quality that allows one

interface to be used for a general class of actions.

The specific action is determined by the exact nature of the situation. A simple example of

polymorphism is found in the steering wheel of an automobile. The steering wheel (i.e., the

interface) is the same no matter what type of actual steering mechanism is used. That is, the

steering wheel works the same whether your car has manual steering, power steering, or rack-

and-pinion steering. Therefore, once you know how to operate the steering wheel, you can drive

any type of car.

The same principle can also apply to programming. For example, consider a stack (which is a

first-in, last-out list). You might have a program that requires three different types of stacks. One

stack is used for integer values, one for floating-point values, and one for characters.

In this case, the algorithm that implements each stack is the same, even though the data being

stored differs. In a non-object-oriented language, you would be required to create threedifferent sets of stack routines, calling each set by a different name, with each set having its own

interface. However, because of polymorphism, in C++ you can create one general set of stack

routines (one interface) that works for all three specific situations. This way, once you know how

to use one stack, you can use them all.


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Inheritance

Inheritance is the process by which new classes called derived classes are created from existing

classes called base classes. The derived classes have all the features of the base class and the

programmer can choose to add new features specific to the newly created derived class.

For example, a programmer can create a base class named fruit and define derived classes as

mango, orange, banana, etc. Each of these derived classes, (mango, orange, banana, etc.) has all

the features of the base class (fruit) with additional attributes or features specific to these newly

created derived classes. Mango would have its own defined features, orange would have its own

defined features, banana would have its own defined features, etc.

Inheritance helps the code to be reused in many situations. The base class is defined and once it

is compiled, it need not be reworked. Using the concept of inheritance, the programmer can

create as many derived classes from the base class as needed while adding specific features to

each derived class as needed.

The above concept of reusability achieved by inheritance saves the programmer time and effort.Since the main code written can be reused in various situations as needed.

Increases Program Structure which results in greater reliability.


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C++ is a compiled language.

This means that before the program is run, it is first translated into a form that the

machine can use directly.

The C++ files (and a typical project contains several) are called the source files. You create

the source files bytyping them using a program called a text editor.

The translation of the source files into a program proceeds in two phases.

First, the individual source files are translated by a program called the compiler into socalled object files. Next, a second program, called a linker (or loader) combines the

individual object files into an executable file, that is, a program you can execute

(run).

The precise manner in which is all this is done (source file creation/editing, compiling,

linking, and execution) varies among different computing platforms.


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The C++ language consists of two basic elements:

Semantics: This is a vocabulary of commands that humans can understand and

that can be converted into machine language, fairly easily.

and

Syntax: This is a language structure (or grammar) that allows humans to combine

these C++ commands into a program that actually does something

(well, maybe does something).

To write a program, you need two specialized computer programs. One (an editor) is what

you use to write your code as you build your .CPP source file.

The other (a compiler) converts your source file into a machine-executable .EXE file that

carries out your real-world commands (open spreadsheet, make rude noise, deflect

incoming asteroid, whatever).

Nowadays, tool developers generally combine compiler and editor into a single package

a development environment. After you finish entering the commands that make up

your program, you need only click a button to create the executable file.


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A computer program is simply a set of instructions to tell a computer how to perform a

particular task.

At the very simplest level it consists of issuing a sequence of commands to a computer to

achieve an objective.

A C++ program is a text file containing a sequence of C++ commands put together

according to the laws of C++ grammar. This text file is known as the source file (probablybecause its the source of all frustration). A C++ source file carries the extension .CPP just

as a Microsoft Word file ends in .DOC or an MS-DOS (remember that?) batch file ends in

.BAT. The concept extension .CPP is just a convention.

Whats a program?

It is not possible to execute this file directly. The source file is passed to a compiler

(a program which generates a new file containing a machine code translation of the source

text). This file is called an object file or executable file.

The executable file is said to have been compiled from the source text.


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All C++ programs are based on what are known as C++ statements.

A statement is a single set of commands. All statements other than comments

end with a semicolon.

A declaration is a statementthat defines a variable. A variable is a holding tankfor a value of some type. A variable contains a value, such as a number or a

character.

For example

int age;

is a declaration statement.

C++ is a case-sensitive:

This means the word name is different from the word Name or any other variations

related to capitalization.

Unlike some other programming languages, such as COBOL, C++ is afree-form language,

meaning that programming statement can start in any column of any line. You can insert

blank lines in a program if you want.


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It may seem odd to have a command in C++ (or any other programming language)

thats specifically ignored by the computer. However, all computer languages have some

version of the comment. Its critical that the programmer explain what was going through

her mind when she wrote the code. A programmers thoughts may not be obvious to the

next colleague who picks up her program and tries to use it or modify it. In fact, theprogrammer herself may forget what her program meant if she looks at it months after

writing the original code and has left no clue.

Single-line comments begin with a double slash // and continue to the end of the line. They

are useful for short comments.

Multiple-line comments may span one or more lines. The comment begins with the pair of

characters /* and ends with */.

#include

Lines beginning with a hash sign (#) are directives for the preprocessor. They are not

regular code lines with expressions but indications for the compiler's preprocessor. The jobof the preprocessor is to read through your source code looking for lines that begin with #,

and when it finds one, to modify the code as requested by that command. These

manipulations usually include other text files to be compiled and perform various text

replacements. This all happens before the compiler sees your code.


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The #include tells the compiler to include the header file iostream.hthe

compiler is smart enough to know about the .h, so you dont have to put it in. This header

file describes what components the library provides so that the compiler can recognize

names such as cout. This header file is part of the C++ system, and so is called a system

header file.

Including the header file for iostream gives you the ability to use the iostream library.

You can open the iostream.h file if you can find it on your system (usually in the

include subdirectory of the directory where your compiler is installed). You will probably

find its source code hard to understand. Fortunately, the compiler doesnt.

The iostream file must be included for any program that outputs data to the screen or

inputs data from the keyboard using C++ style stream input/output. It also includes the

declaration of the stream inserter (


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The cout object: This is an object to which we send information that we want written on

the computer screen. The word cout is an abbreviation of console output.

The


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The object cout is not core part of C++, but standard addition to the language. It is possible

that a software developerlets call her Sophiemight want a different version ofcout that is

somehow different from the standard version.

Sophie also wants to call her console output object cout; this is possible in C++. Sophie creates

(dont worry about how, you are not a software developer) a separate namespace, which she

calls, say, sophie. Each namespace itself has a name that is added to any names in the code it

holds. Therefore, the full name of Sophies cout is sophie::cout. Similarly, the full name of the

standard cout is std::cout, where std stands for the standard namespace.

We can say that namespaces are a sort of container for names (or objects).

In the iostream file, cout is defined to have the full name std::cout. It is possible to

delete line using namespace std; from the program, but then it would be necessary to

replacecout with std::cout. However, for our purposes, it is much easier to declare: we are

going to be using the standard namespace, so we will use the short forms of the names. Thats

what the statement using namespace std; does.


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The statement using namespace std tells the compiler, If you see a name and you

dont know what namespace it is from, assume it is from the std namespace.

If you leave this command out, you will get the following message from the compiler:

error : cout was not declared in this scope

This is because the compiler does not know where to look for cout. Since we never

mention the namespace in which they can be found.

We could cure this without the using namespace statement by changing

line to std::cout


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The basic building block in a C++ program is thefunction.

The term function refers to a task or job.

Every C++ program is a collection of one or more functions, written in some arbitrary order.

One and only one of these functions in the program must have the name main().

C++ program always start its execution at the function named main.

It doesnt matter if main is physically located at the beginning or end of your source code.

Functions take various values as arguments, execute instructions, and return a value. In this

case, the function named main returns an integer value; this is signified by the word int

before the name of the function.

The value returned is zero, and this is accomplished at the end of the function with thestatement return 0; which returns the value 0.


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The main function does not take any arguments; this is signified by the empty pair of

parentheses following the word main.

The main function defined as : main() { }

int main() // function header, no semicolon

{ // start of function body

return 0; // C++ statement, requires semicolon

}//

end of function body

The function definition is the combination of the function header and the function body.

A function header is the first line in a function definition.

The function body contains the statements enclosed in curly braces.


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The function main() does not have to be at the top of a program so a C++ program does not

necessarily start at line 1. It always starts where main() is.

Also, the function main()cannot be called from any other function in the program.

Only the operating system can call the function main(): this is how a C++ program is started.


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Escape Sequence:

Non graphics characters (characters that can be

typed directly from keyboard e.g. backspace, tabs,

carriage return etc.) can be represented by using

escape sequences.

An escape sequence is represented by a backslash (\)followed by one or more characters.

An escape sequence is represents a single character.


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Escape Sequence: Non graphic character

\a Audible bell (alert)

\b Backspace

\n Newline or linefeed

\t Horizontal tab

\v Vertical tab

\\ Backslash

\ Single quote

\ Double quote

\0 Null character

A null character is a special character, used among other things to give a

character variable an initial value.


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What will be the output of the following C++ code:

#include

using namespace std;main()

{

cout


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The following comment in a C++ program would cause the compiler to issue

an error message.

/*

* In C++ comments are enclosed between /* and */

*/

Whats wrong?

For the following code, indicate if there are any errors. If there is an error,

specify how you fix it:

1. \\ This is my first program

2. /* this is the example of multi line Comment/*

3. /* Isnt this /* a fun */ comment */

4. int main();

5. int main( )

(

return 0 ;

)


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int main()

{

return 0

} end of main() function

Numbers are the building blocks of mathematics and, of course, computers are extremely

adept with numbers. There are several ways in which numbers are handled in C++.

Numbers in C++ are divided into two broad categories: integers and reals.

Each of these categories is refined further. Of course, to a mathematician every integer is a

real number, so these categories may seem spurious.

The reasons for having many different ways to represent numbers are efficiency and

accuracy; if the quantities with which we are computing are known to be integral, then using

an integer representation is not subject to roundoff error and the computations are faster.


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Literals:

Literals (often referred to as constants) are data items thatnever change their value during a program run.

C++ allows several kinds of literals:

Literals

Integer

Decimal Octal Hexadecimal

Floating Character String


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Variables:

Avariable is a placeholder whose contents can change. A placeholder is given a name, which we use reference the

value stored in the variable.

Every variable name in C++ must start with a letter, the rest ofthe name can consist of letters, numbers and underscorecharacters.

It can not contain any blanks, commas or special symbols,such as ()!?.

C++ recognizes upper and lower case characters as being

different. you cannot use any of C++ keywords like main, while, switch

etc. as variable names.


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Examples of Variable Names:

Valid Variable Names:

Idnumber

sumofnumbers

I, j, k1transaction_number

phone_number

CASENO

Invalid Variable Names:

4myfriend

sum of two no

s.no

T1_

amount@1

while

write


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Every variable in a C++ program must be given a type.

The type of a variable is a specification of the kind of data the variable can store. The most

basic type is int.

An int represents an integer quantity.

In this program, two variables, x and y, are declared to be of type int.

C++ requires that we specify the type of every variable, and the declaration statement is the

manner by which this is accomplished.. Variables may be declared anywhere in the program so

long as they are declared before they are used.

Subsequently the variables are assigned values.

In this case x is assigned the value 3 and y the value 4.

The equal sign = is an operation (called assignment) that stores the value of the expression toits right into the variable on its left.


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It is possible to combine declarations on a single line; in place of lines 6 and 7, we could have

this:

int x,y;

It is possible to combine declaration with assignment. Lines 910 can be replaced by these two:

int x = 3;

int y = 4;

In line 12, the contents ofx and y are added, and the result is written on the computers screen.

Variables of type int can store a finite range of integer values. The size of that range depends

on your specific computer.

On many computers an int is held in 4 bytes of memory (one byte is 8 bits, so this is 32 bits).

With 32 bits one can store 232 different values.


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There is an easy way to learn the size of an int on your computer in C++ with the sizeof

operator. Evaluating sizeof(int) gives the number of bytes used to store variables of type

int.

There are a few variations of the fundamental int type.

A short is an integer type that is either the same as int, or else a smaller size than int.

That is, sizeof(short)cannot exceed sizeof(int).

There are a few variations of the fundamental int type.

A short is an integer type that is either the same as int, or else a smaller size than int.

That is, sizeof(short) cannot exceed sizeof(int).

A long is an integer type that is either the same size as int, or else a larger size than int. In

other words, sizeof(long) is at least sizeof(int).

Some compilers provide a long long type. This is an integer type that is at least the size of

a long. That is, sizeof(long long)cannot be less than sizeof(long).

In summary,

sizeof(short) sizeof(int) sizeof(long) sizeof(long long).


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C++ provides header files with this information. The header file climits gives the minimum and

maximum value of various integer types. It defines symbols such as INT_MIN and INT_MAX that

are equal to the smallest and largest value an int may hold. Similarly, the header file cfloat gives

the minimum positive, maximum, and epsilon values for float, double, and long double (if

available) data types.


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The bool and char types

There are other basic data types available in C++. Two that we encounter frequently in C++ are

designed for handling Boolean and character data.

The data type bool is used to represent the logical values TRUE and FALSE. In C++, these arerepresented as integers: 1 for TRUE and 0 for FALSE. Indeed, bool is considered to be an

integer type.

Boolean values emerge as the result of comparison operations. In C++, to see if two variables

hold equal values we use the == operator.

The result of x == y is either 1 (TRUE) in the case where x and y hold equal values and 0

(FALSE) otherwise.

If your program contains the statement

cout


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Individual characters have the type char. One can create variables to hold single characters

by declaring them to be of type char as shown below:

char x;

x = A;

cout


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Exercises:What is wrong with each of the following declaration

statement:1. int a, int b;

2. int a = 0, b = 4.5;

3. char grade = A;

4. char title = this is first test program;

5. int base_salary (30000)

int id_num, staff_salary = base_salary;

6.float area, circumfrence;


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C++Constants:

ANSI C++ allows you to declare constants.

A constant is similar to a variable in the sense that it

represents a memory location.

It differs, in that it cannot be reassigned a new value after

initialization.

The const keyword is to declare a constant, as shown below: int const a = 1; or const int a =2;

const double PI = 3.1416;

Note: You can declare the const before or after the type.

It is usual to initialize a constant with a value as it cannot get a value any otherway.


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There are three techniques used to define

constants in C++:

Using #define

Using const variables

Using Enumerated Data Types


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Example:// defined constants: calculate circumference

#include using namespace std;

#define PI 3.14159

int main ()

{

double r = 5.0; // radius

double circle;

circle = 2 * PI * r;

cout


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Standard operations

C++ provides the familiar arithmetic operations. The expressions x+y, x-y, x*y, and

x/y are the usual sum, difference, product, and quotient ofx and y.

In these expressions, x and y may be any of the numeric types we discussed.

However, mixing types can sometimes cause problems and confusion. Ifx and y are of the

same type, then the result of the operation is also that type. For example, consider the

following code:

int numerator = 13;

int denominator = 5;

double quotient;

quotient = numerator/denominator;

cout


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We might expect this code to print the value 2.6 on the computers screen. The

surprise is that the computer prints 2. To understand why, we have to remember

that when two int values are divided, the result is an int.

In this case, C++ divides the integers 13 and 5 to give the result 2 (the fractionalpart is lost) and then assigns that value to quotient.

Because quotient is of type double there is a silent, behind-the-scenes conversion

of the int quantity into a double quantity.

We can coerce C++ to give us the answer 2.6 by converting 13 or 5 (or both) into

double variables. We replace quotient = numerator/denominator with this:

quotient = double(numerator) / double(denominator);

The expression double(numerator) converts the integer value in numerator into a

double quantity. This conversion process is known as casting. Note that the variables

numerator and denominator are unaffected by this; they remain type int and their typecannot be changed. What double(numerator) does is create a temporary double

number to be used in the division.


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