introduction to c++ by dk mamonai 09ce37

8/6/2019 Introduction to C++ by Dk Mamonai 09CE37

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TOBECOMEFAMILIARWITHBASICSOF C++ PROGRAMMINGAND IDE ENVIRONMENT.

OBJECT 1: INTRODUCING C++ ENVIRONMENT

The C++ environment is the graphical user environment as it offers the capability of themouse. Like many application environments C++ environment is a window with workarea and formatting tool bar at the top. The blue area in the environment is the texteditor where the user writes source code (program). The cyan colored area below the

text editor is the message window in which the compiler shows the list of errors,messages and warnings. The green button at the left top of the text editor is the close

button, which when pressed closes the current source file and the green arrow at theright top is the minimize/maximize button. The name at the top-center is the name of

the source file with extension of the current activated source file.

The formatting bar at the top works same as in many other applications. To open a newsource file open File menu and click New, to open an existing source file click Open, to

save a source file click Save, to make a duplicate copy of the source file click Save As, toquit from the C++ environment click Exitor pressAlt+X. To compile the current source

program open Compile menu and click Compile or press F9 key while holding down theAltKey. To run the current source program open Run menu and click Run or press F9

while holding down the Ctrlkey.

In C++ text editor you can copy, paste, cut or delete certain block of code with some

hotkeys. Hotkeys for copy, paste, cut and delete are Ctrl+Insert, Shift+Insert,Shift+Delete, Ctrl+Delete respectively.

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BASIC C++ PROGRAM

Whenever you start any objective you first deal with the basics because the basics areroots through which you can gain command on that objective. So here also we will startwith a basic source program. You can write any C++ source program into the C++

editor or any other text editor like, Notepad or WordPad. Remember one thing that allthe C++ source files have the extension .cpp. let us examine this simple C++ source

program named (basic.cpp):

Program (basic.cpp)

#include

#include

void main()

{

clrscr();cout


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the ending of the main or any function. The code of each and every function is alwaysenclosed in the curly braces.

The function clrscr() is used to clear the console screen. As you work repetitively withthe console screen and output your results continuously with out rubbing the previousoutput your console screen would be filled with a lot of text and your console screen will

not fit your new output correctly and you also will not be able to examine your outputclearly. So the clrscr() function helps to clean the console screen.

The cout


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OBJECT 2: VARIABLES, DATA TYPESAND CONSTANTS

VARIABLES

The basic definition of the variable says that the variables are those memory locations

whose value can be varied/altered according to the particular situations. Like in otherprogramming languages variables are one of the major building blocks of C++

programming language. The variables set the location into the memory and give itcertain name so you can store certain value and access the particular location of

memory. The name given to the variable is known as identifier. It is so called because itidentifies/indicates certain memory location. In C++ programming language there arecertain rules for identifiers so, being in the boundary of those you can declare anidentifier.

Some of the rules are given as:

1) The identifier can contain letters form a-z, numbers form 0-9 and an underscore

sign.

2) The identifier can be in upper or lower case but the variable in upper case will differ

from the variable in lower i.e.ANS is not same as ans orAns.

3) The first character of the identifier must be letter or an underscore sign.

4) The identifier should not contain any space (white space) within it.

5) You can also give underscore sign in the middle of the identifier as an space for

your ease for example, square_inch.

6) The identifier must not be same as the keywordsthe words predefined in C++

which have their own specific meaning and function. Like, main, void, return, cout,

cin etc. are keywords so the identifier should not be like them.

7) The identifier can be as long as you like, but only the first 247 characters (in Visual

C++) or 250 characters (in C++ Builder) will be recognized.

8) The identifier must be unique through out the program i.e. if you have declared the

identifier Var1 so, to access or call it you must give its same name i.e. Var1.

Some valid identifiers are:

Var, var, VAR, Var1, VAR1, Var_one, _Var1, _Var_one_of_one etc.

Some of invalid identifiers are:

1Var, 1_var, void, cout, etc.

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DECLARINGAND DEFININGAVARIABLE

You might think that the two words declaring and defining are equivalent but in factthere is a lot of difference between both of them. The declaring is the process of giving aname to the variable and its data type. The data type means that which type of valuewill be stored in that variable where as the name of the variable must follow the

identifier rules of C++.

int var1;

The above line is an example of declaring a variable in which the variable is given thename var1 and integer data type declared for it which tells the computer that the value

stored in the variable var1 must be an integer.

Where as the process of initializing certain value to the variable at the time ofdeclaration is referred to as defining a variable. The line below illustrated the concept of

defining a variable:

int var1=50;

In above line the variable var1 is initialized with the integer value 50.

In defining a variable we set/initialize some values to the variable before the compiling.

Memory Memory

var1 var1

Variable Declared Variable Defined

int var1; int var1=50;

50

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Examine the below program (Var.cpp) which initializes and declares some variables:

Program (Var.cpp)

#include #include

void main()

{

clrscr();

int mixture;

int ethane=5, methane=8, propane=2;

mixture=(ethane + methane + propane);

cout


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The variables are the fundamental building blocks of C++ as discussed earlier, which set

the memory location by giving them certain names. The variables can store certaindata/values into those memory locations but the data/values stored in to the variablesare of different types and occupy different sizes of memories.

INTEGERDATATYPES

The numeric data having no fractional/decimal part is known as integer data. The

integer data type variables can only store and represent integer data. The integer datatype is of three types i.e. type int, type shortand type long.

Type intoccupies 4 bytes (32 bits) of memory. In type int you can store the integers

with in the rage of -2,147,483,648 to 2,147,483,647. To define or declare a type intvariable use the keyword intbefore the variable name like,

int var1= 100000000;Type short occupies 2 bytes (16 bits) of memory. In type short you can store theintegers with in the range of -32,768 to 32,767. To define or declare a type short

variable use the keyword shortbefore the variable name like,

short var1=10;

Type long occupies 4 bytes (32 bits) of memory. In type long you can store the integerswith in the rage of -2,147,483,648 to 2,147,483,647. To define or declare a type long

variable use the keyword long before the variable name and place the letter L after the

integer constant like,

long var1=100000000L;

Program (integer.cpp)

#include

#include

void main()

{

int a=10000;

long b=20000;

short c=5;

cout


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The numeric data having fractional/decimal part is known as floating point data. The

floating point data type variables can store and represent floating point data. Thefloating point data type is of three types i.e. type float, type double and type longdouble.

Type floatoccupies 4 bytes (32 bits) of memory. In type float you can store the floating

point values with in the range of 3.8 x 10-38 to 3.8 x 1038 with the precision of seven (7)

digits. To define or declare a type float variable use the keyword float before the

variable name and place the letter Fafter the floating point constant like,

float PI=3.1415F; but placing Fis optional.

The other two floating point data types are same as type float but they offer wider range

of values and precisions.

Type double occupies 8 bytes (64 bits) of memory. In type double you can store the

floating point values with in the range of 1.7 x 10-308 to 1.7 x 10308 with the precision of

fifteen (15) digits. To define or declare a type double variable use the keyword doublebefore the variable name like,

double PI=3.141592654;

Type long double occupies 10 bytes (80 bits) of memory. In type long double you can

store the floating point values with in the range of 1.2 x 10-4932 to 1.2 x 104932 with the

precision of nineteen (19) digits. To define or declare a type long double variable usethe keyword long double before the variable name and place the letter L after the

floating point constant like,

long double PI=3.141592654546845348645454L; but placing L is optional.

In floating point data types you can write the floating point constants using exponential

notation, which is the way to write very large or very small numbers in the power of ten.Like instead of writing 2,000,000,0 you can write 1.0E7 in exponential notation.

Similarly for 52347.2 you can write 5.2E4 and for 0.0000006024 you can write 6.02E-7.

double atoms=6.02E-7;

If you want to define a floating point variable then in type floatplace a letter F in theend of the constant number, in type double you dont have to identify the complier thatit is a constant value it considers it as default but in type long double you have to place

the letter L after the constant number. But placing Fand L is optional.

float PI=3.1415F;

double PI=3.141592654;

long double PI=3.141592654546845348645454L;

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You can also make the value of the floating point variable constant through out thefunction by using the constant qualifier i.e. const. To define a constant floating point

variable place the keyword const before the data type of the variable as in:

const float PI=3.1415F;

const double PI=3.141592654;

const long double PI=3.141592654546845348645454L;

Examine the following program:

Program (area.cpp)

#include

#include

void main()

{


int radius;

float area;

coutradius;

area=PI*(radius*radius);

cout


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The data containing individual characters is known as character data. The character data

type variables can only store and represent the characters. The character data typevariables can only store single character at a time in a single variable.

Type charoccupies 1byte (eight bits) of the memory. In type char you can store the

characters within the range of integers -128 to 127, where as the integers -128 to 127represent the ASCII equivalents to the characters. To declare a character data type use

keyword charbefore the variable name as in,

char ch;

The above declaration indicates that the variable ch is a character type data variable andin the program it will only store the characters. And to define a variable you can eithergive the character in single quotation marks or you can give the ASCII equivalent to that

character. For example if we want to store the character A (capital A letter) in thevariable ch then we can write as in,

char ch=A;

char ch=65;

In first line the characterA is enclosed in single quotation marks so the characterA willbe store in the variable ch where as in second line the number 65 is the ASCII

equivalent to the characterA so the computer will translate it in to characterA and willstore it in the variable ch. No matter which method you perform the aim of both the

methods is same.


Program (char.cpp)

#include

#include

void main()

{

char ch;

coutch;

cout


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Numerical Range Digits of Bytes ofKeyword Low High Precision Memory

char -128 127 n/a 1

short -32,768 32,767 n/a 2

int -2,147,483,648 2,147,483,647 n/a 4

long -2,147,483,648 2,147,483,647 n/a 4

float 3.4 x 10-38 3.4 x 1038 7 4

double 1.7 x 10-308 1.7 x 10308 15 8

long double 1.2 x 10-4932 1.2 x 104932 19 10

UNSIGNEDDATATYPES

The data types int, short, long and charhave their range with in which they can storecertain values and these ranges start from some negative number to positive number.

So by eliminating negative numbers we can extend the size of the data types. Doing thiswill make the data types to store large values as twice as the signed data types do.

The unsigned data types are used when we are dealing with only positive numbers. Toconvert a signed data type into an unsigned data type place the keyword unsignedbefore the data type as in,

unsigned int var1=12000;

Type unsigned charoccupies 1 byte (8 bits) of memory. In type unsigned char you canstore the characters within the range of integers 0 to 255, where as the integers 0 to255 represent the ASCII equivalents to the characters. To declare an unsigned char data

type variable use keywords unsigned charbefore the variable name as in,

unsigned char ch=250;

Type unsigned shortoccupies 2 bytes (16 bits) of memory. In type unsigned short youcan store the integers within the range of 0 to 65,535. To declare an unsigned short

data type variable use the keywords unsigned shortbefore the variable name as in,

unsigned short var1=50;

Type unsigned intand type unsigned long occupy 4 bytes (32 bits) of memory. In both

the data types you can store the integers within the range of 0 to 4,294,967,295. Todeclare an unsigned int and unsigned long data type use the keywords unsigned intand

unsigned long respectively before the variable names as in,

unsigned int var1=10000;


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unsigned long var1=10000;

Table 1.2, Unsigned data types and their ranges.

Numerical Range Bytes ofKeywords Low High Memory

char 0 255 1

short 0 65,535 2

int 0 4,294,967,295 4

long 0 4,294,967,295 4

THE CONST QUALIFIER

The keyword const is known as the constant qualifier. It specifies that the value of thevariable will remain constant and will no be altered through out the function. If any

attempt is made to alter the value of the variable the compiler will give the error. It isalways placed before the data type of the variable as in,


It specifies that the variable PIstores the floating point number 3.1415 and this value

will not be altered and will remain constant.


Program (const.cpp)

#include

#include

void main()

{

const int a=15;

int b=10,c;

b=b+1;

c=a+b;

cout


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ARITHMETIC OPERATORS

The arithmetic operators are those who perform some arithmetic operations on thenumbers. There are five arithmetic operators +, -, *, / and %. These are used foraddition, subtraction, multiplication, division and remainder respectively. They have the

same purpose in C++ as in other languages. The first four operators have the samefunctionality as they posses in algebra. The fifth operator is known as remainder

operator it finds the remainder when one number divides another. It is also known asmodulus operator. It is denoted by % percentage sign. The first four arithmetic

operators work on all data types but the remainder operator only works on integervariable (type short, type int, type long).

Program (arith.cpp)

#include #include

void main()

{

int a=10, b=5;

cout


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The operators used in assignment statements to shorten and clarify the code are knownas arithmetic assignment operators. They are +=, -=, *=, /= and %=. In some

situation probably you would have faced some statements like,

a=a+b;

b=b-10;

var1=var1*50;

var1=var1/var2;

In these statements a certain value is given to a variable by performing some arithmeticoperation but one variable is used twice in the statements which is really stretchingtherefore C++ also offer other approach to shorten and make the assignmentstatements more clearer. In this approach you can use the arithmetic assignment

operators +=, -=, *=, /= and %= which have the same effects as above.

In C++ a=a+1; and a+=1; have the same effects. Some other equivalents are,

electrons += 1; is same as electrons=electrons+1;electrons -= 1; is same as electrons=electrons-1;

electrons *= 1; is same as electrons=electrons*1;

electrons /= 1; is same as electrons=electrons/1;

electrons %= 1; is same as electrons=electrons%1;

Program (arithassign.cpp)

#include

#include

void main()

{

int boxes=40;

cout


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The relational operators are the operators which compares the operands. There are onlytwo possible values that the relational operators can give after performing the operation

on the operands i.e. 0 or 1. If the condition becomes true when the operands arecompared with relational operators we get the value 1. On the other hand if thecondition becomes false when the operands are compared with relational operators weget the value 0. There are six relational operators they are, Greater than >, Less than

=, Less than or equal to


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Logical operators logically combine the Boolean variables (0 and 1). There are threelogical operators And &&, OR || and Not !. They have wide scope when used with

relational operators. They combine the Boolean value obtained by relational operators.Like in relational operators we can only compare two operands and get the true or falsevalue of only single comparison but if we want to make the condition satisfied only whenthe two or more comparison are satisfied then we use logical operators.

And && operator combines the Boolean values and makes the condition satisfied only

when all the comparisons are satisfied as,

(a>b && a>c && a>d)

OR || operator combines the Boolean values and makes the condition satisfied whenatleast one comparison becomes true as,

(a>b || a>c || a>d)

Not ! operator combines the Boolean values and makes the condition satisfied only whenall the comparisons become false as,

(!(a>b)&& !(a>c)&& !(a>d))

Program (logic.cpp)

#include

#include

void main()

{int a=2, b=3, c=4;

coutc)


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1) Write a program that will compute the area of a circle. The user must enterthe radius of the circle. Use the following formula for area A=3.14*R^2?

2) Write a program that will solve for the power dissipation of a resistor when thevoltage across the resistor and the current in the resistor are known. The relationship

for the power dissipation is: P=I^2*R?

3) Write a program that calculates the memory size of variable of different datatype?

4) Develop a program that will convert the temperature from degree Celsius todegree Fahrenheit. User input the temperature in Celsius. The relation is

F=5/9*C+32?

5) (a): Execute the following code step-by-step using F8 key and observe howthe integer variables are declared, initialized and modified in the program.

#include

void main()

{

int i=0;

int j=1;

cout


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EXERCISESOLUTIONS

====================================================

Program #01

#include

#include

void main()

{

const float PI=3.14;

int radius;

float area;

coutradius;

area=PI*(radius*radius);

cout


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====================================================

Program #03

#include

#include

void main()

{

char a;

short b;

int c;

long d;

float e;

double f;

long double g;

cout


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====================================================

Program #05(a)

#include

void main()

{

int i=0;

int j=1;

cout

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