Basic Elements of C++

04/10/231 VIT - SCSE

By

G.SasiKumar., M.E., (Ph.D).,Assistant Professor

School of Computing Science and EngineeringVIT University

Characters are used to form the words, numbers and expressions.

 alphabets from A.....Z, a....zall decimal digits from 0....9characters , . ; : ?

‘ “ ! | / \ ~ _ $ % # & ^* - + < > ( ) [ ] { } SpacesblankNew Line endl

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Character Set

Keywords and IdentifiersAll keywords must be written in lowercase.

auto double int struct breakelse long switch case enum registerTypedef char extern return unionconst float short unsigned continuefor signed void default gotosizeof volatile do if static while

Identifiers refer to the names of variables, functions and arrays.

These are user -defined names and consist of a sequence of letters and digits.

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Data Types

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C++ Data Types

User Defined type

StructureUnionClassEnumeration

Built-in type Derived type

ArrayFunctionPointer

Integral Floating Character

Void

byte short int longfloat double

ConstantsConstants in C++ refer to fixed values that do

not change during the execution of a program.C++ supports several types of constants as

shown below: -1. Numeric Constants

Integer ConstantsFloating point (real) Constants

2. Character ConstantsSingle Character ConstantsString Constants

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Integer Constants Decimal integers consist of a set of digits

from 0 through 9. The decimal integers can be positive or negative.(base 10)

Octal integers consist of any combination of digits from 0 through 7, with a leading zero.(base 8)

Hexadecimal integers consist of a sequence of digits 0 through 9 and alphabets from A (a) through F (f). The letters 'A' (a) through 'F ' (f) represent the integers 10 through 15.(16)

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Floating-Point Constants

Floating-point constants are represented by numbers containing fractional parts like in 549.4545.

Floating-point constants are also sometimes called as real number constants.

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Single Character ConstantsA character constant is a single character enclosed

within a pair of single quotes.Example:

'A''3''?'';'' '

Constant ASCII value'a' 97'A' 65'&' 38';' 59

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String Constants A string constant is a sequence of

characters enclosed within a pair of double quotes.

The string constant may also include special characters, numbers and blank spaces.

Example:" Hello!"" I'm going for shopping today. Will you

come?"" 549, The Mall, Shimla."

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Escape SequencesCharacter Escape sequence

bell \abackspace \bhorizontal tab \tvertical tab \vnewline \ncarriage return \rquotation mark \"apostrophe \'backslash \\null \0

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VariablesA variable is an identifier that is used to

represent a single data itemDeclarationDefinition

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OperatorsAn operator is a symbol that tells the compiler to

perform specific mathematical or logical manipulations.

Arithmetic OperatorsoIncrement and Decrement Operators

Relational and Logical OperatorsAssignment OperatorsTernary(Conditional) OperatorSizeof OperatorComma Operator& Operator -> Operators(a->b -Member b of object pointed to by a )

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Control StatementsConditional Statements

If statementIf-else statementSwitch-case statement

Loop StatementsFor loopWhile loopDo-while loop

Breaking control statementsBreakContinuegoto

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Switch statementswitch(expression){ case constant_1:

statement;break;case constant_2:statement;break;-----------------case constant_n:statement,break;default:statement;break;}

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//A program to display the name of the day in a week, depending upon the number entered through the keyboard using the switch-case statement.

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#include<iostream.h>void main(){int day;cout<<”Enter a number between 1 to 7”<<endl;cin>>day;switch(day){case 1:cout<<”Monday”<<endl;break;case 2:cout<<”Tuesday”<<endl;break;

case 3:cout<<”Wednesday”<<endl;break;case 4:cout<<”Thursday”<<endl;break;case 5:cout<<”Friday”<<endl;break;case 6:cout<<”Saturday”<<endl;break;case 7:cout<<”Sunday”<<endl;break;}}

For statement//A program to find the sum and average of given numbers.

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#include<iostream.h>void main(){int n;cout<<”How many numbers?”<<endl;cin>>n;float sum=0;float a=0;float a;

for(int i=0; i<=n-1;i++){cout<<”Enter a number”<<endl;cin>>a;sum=sum+a;}float av;av=sum/n;cout<<”sum=”<<sum<<endl;cout<<”Average=”<<av<<endl;}

Nested For StatementA program to display a name 15 times using the nested for

loops.#include<iostream.h>void main(){cout<<”Nested for loop”;for(int i=0; i<=2; i++){cout<<i; for(int j=0;j<=2;j++){cout<<j;for(int k=0;k<=2;k++){cout<<k;}}}}

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While statement{sum+=digit;digit++;}cout<<“1+2+3+.....

+100=“<<sum<<endl;

}

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//program to find the sum of the first 100 natural numbers

#include<iostream.h>

void main(){int sum,digit;sum=0;digit=1;while(digit<=100)

Do while loopdo{sum=sum+digit;digit=digit+2;}while(digit<=max);cout<<“2+4+...=“<<m

ax<<“sum=“;}

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//program to find the sum of the even numbers using do-while loop. #include<iostream.h>void main(){int max,sum,digit;digit=2;cout<<“enter a number“;cin>>max;sum=0;

Break statementif(a<=0){cout<<”Zero or negative

value found”;break;}i++;}}

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#include<iostream.h>void main(){int a,i;i=0;while(i<=10){cout<<”Enter a number”<<endl;cin>>a;

Continue statementif(a<=0){cout<<”Zero or negative

value found”;continue;}i++;}}

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#include<iostream.h>void main(){int a,i;i=0;while(i<=10){cout<<”Enter a number”<<endl;cin>>a;

Goto statementoutput1:cout<<”largest value=”<<a<<endl;goto stop;output2:cout<<”largest value=”<<b<<endl;stop:getch();}

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#include<iostream.h>#include<conio.h>void main(){int a,b;cout<<”Enter two numbers;cin>>a>>b;if(a>b)goto output1;elsegoto output2;

goto label;