Object Oriented Programming

Unit 2 :-Control Structure

Decision making Statement
if -else:-

The if statement evaluates the test expression inside parenthesis.
If test expression is evaluated to true, Then statements inside the body of if is executed.
If test expression is evaluated to false, Then statements inside the body of if is skipped(not exicute).

 

 

 

 

 

 

 

 

 

 

// Program to print Even number entered by the user

// If user enters Even number, it is skipped
#include <iostream.h>
int main()
{ int number;
cout << "Enter an integer: ";
cin >> number; // checks if the number is positive
if ( number%2==0)
{ cout << "You entered a Even integer: " << number << endl;
}

getch();
return 0;}

else if

// Program to print Even number Or Not entered by the user

// If user enters Even number,then print number is even else odd
#include <iostream.h>
int main() { clrscr();
int number; cout << "Enter an integer: ";
cin >> number; // checks if the number is positive
if ( number%2==0)
{ cout << "You entered a Even integer: " << number << endl; }
else{cout<<"You entered a Odd integer: " << number << endl;}

return 0;
getch(); }

C++ Nested if…else

The if...else statement executes two different codes depending upon whether the test expression is true or false. Sometimes, a choice has to be made from more than 2 possibilities.

The nested if...else statement allows you to check for multiple test expressions and execute different codes for more than two conditions.

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Syntax of Nested if…else

if (testExpression1)
{ // statements to be executed if testExpression1 is true }
else if(testExpression2)
{ // statements to be executed if testExpression1 is false and testExpression2 is true }
else if (testExpression 3)
{ // statements to be executed if testExpression1 and testExpression2 is false and testExpression3 is true }
. .
else { // statements to be executed if all test expressions are false }

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Example 3: C++ Nested if…else

// Program to check whether an integer is positive, negative or zero
#include <iostream.h>
int main()
{ clrscr();
int number;
cout << "Enter an integer: ";
cin >> number;
if ( number > 0)
{ cout << "You entered a positive integer: " << number << endl; }
else if (number < 0)
{ cout<<"You entered a negative integer: " << number << endl; }
else { cout << "You entered 0." << endl; }
cout << "This line is always printed.";
return 0;

getch();
}

Output

Enter an integer: 0
You entered 0.
This line is always printed.

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Conditional/Ternary Operator ?:

A ternary operator operates on 3 operands which can be used instead of a if...elsestatement.

Consider this code:

if ( a < b ) { a = b; }
else { a = -b; }

You can replace the above code with:

a = (a < b) ? b : -b;

The ternary operator is more readable than a if...else statement for short conditions.

Switch case 

switch case is used in basicly Menu drive programing

example:-write a program for add,sub,multiple

#include<iostream.h>
#include<conio.h>
#include<process.h>//for exit(0);
int main()
{ int a,b,add,sub,mul,ch;
cout<<“1:-Addition”;
cout<<“2:-Subtraction”;
cout<<“3:-Multiple”;
cout<<“4:-EXIT”;
cin<<ch;
switch(ch)
{ case 1:  cout<<“enter two no:-“;
cin>>a>>b; add=a+b;
cout<<“addition=”<<add;
break;//for out the case
case 2:  cout<<“enter two no:-“;
cin>>a>>b; sub=a-b;
cout<<“subtraction=”<<sub; break;
case 3:
cout<<“enter two no:-“;
cin>>a>>b; mul=a*b;
cout<<“Multiplication=”<<mul;
break;
case 4:   exit(0);
break;   } // end of switch
getch(); }




FOR LOOP

Syntax:-   for(initialize;condition;increment/decremenr)
Flow Chart

Example:-write a program to print table?

#include<iostream.h>
#include<conio.h>
int main()
{
int no,table,i;
cout<<"enter a number";
cin>>no;
for(i=1;i<=10;i++)
{
table=no*i;
cout<<no<<"*"<<i<<"="<<table;
}
getch();
}

output:-
enter a number:-5
5*1=5
5*2=10
5*3=15
.....
.....

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