Logic operators in c++

&& - and operator
||- or operator
! - not operator


Program 1:- To find greatest among three numbers


#include <iostream>
using namespace std;
int main ()

{

    int a,b,c;

    cout<<"enter any three numbers a,b,c"<<endl;
    cin>>a>>b>>c;


    if(a>=b && a>=c)
    {
        cout<<"a is greatest number";
    }


      if(b>=a && b>=c)
    {
        cout<<"b is greatest number";
    }



      if(c>=a && c>=b)
    {
        cout<<"c is greatest number";
    }


    return 0;


}

Mathematical functions


Required header:  #include <cmath>

in programming languages, loops are used to execute a set of statements repeatedly, until a particular condition is satisfied.

There are 3 kind of loops in c++
1. While loop
2.For loop
3.Do-While loop


1.While loop


Example1:-counting from 0 to 9 (using while loop)




#include <iostream>
using namespace std;

int main()
{
    int x=0;

while (x<=9) {
        cout << x<<endl;
        x=x+1;
    }

    return 0;
}









































The same code can be executed by for loop as well



2.For LOOP


syntax :-

   for ( intitiation point ; termination point ;  increment or decrement)

    {condition;
}


Example 1:-counting from 0 to 9 (using for loop)

#include <iostream>
using namespace std;
int main ()

{
    int x=0;

    for ( x=0; x<=9; x=x+1)

    {cout<<x <<endl;
}


    return 0;

}







































Example 2:-Multiplication table

#include <iostream>
using namespace std;
int main()

{

    int a;
    cout << "Enter a positive integer: ";
    cin >> a;

    for (int b=1; b<= 10; b=b+1)

    {
        cout << a << " * " << b << " = " << a * b << endl;
    }

    return 0;

}


















































3.Do while loop


The same program that counted 0-9,,,, can also be made using this loop..

The especiality of do while loop is that it tests the condition at last,, whether its true or not..


syntax :-

do{statements;

}
while ( conditions) ;

dont forget the semicolon after while statement

Example 2:-counting from 0 to 9 (using do-while loop)
    

#include <iostream>
using namespace std;
int main()

{

int x=0;

do {cout<<x<<endl;
x=x+1;}

while (x<=9) ;

    return 0;

}















































in next lesson you will learn about mathematical functions

Mathematical functions in c++

1.If Statement

it is a conditional statement.. The if statement is used to execute the code, only when a condition is true.

if (condition) 

{ 

statements

}



Example 1. checking if a number is greater than 100


#include <iostream>
using namespace std;
int main ()

{
 int a;

   cout << "enter the number \n" ;
        cin >> a;


    if (a>100)
    {
        cout<<"yes the number is greater than 100" ;
    }


    return 0;


}














































similarly you can use

>=       greater than or equal to 
<=       less than or equal to
equal to==
!=        not equal to




Example 2. checking the greater number out of two

#include <iostream>
using namespace std;
int main ()

{
    int a;
    int b;

    cout<< "enter a number a\n" ;
    cin>> a;

    cout << "enter another number b\n" ;
    cin>> b;

    if (a>b)
    {
        cout<< "a is greater than b";
    }


    if (b>a)
    {
        cout<< "b is greater than a" ;
    }


    if (b==a)
    {
        cout<< "both are equal" ;
    }

    return 0;

}
























































2.If-Else Statement

if (condition)

{ statements}
else
{statements}



Example 1. fail/pass in an exam

#include <iostream>
using namespace std;
int main ()

{

    int marks;


    cout << "enter your marks\n" ;
    cin>> marks;


    if (marks<33)

    {
        cout<< "failed";
    }

    else
    {
        cout<<"passed\n" << "congratulations";


    }

    return 0;
}




















































3.Nested If Statements


#include <iostream>
using namespace std;
int main ()


{
    int age;

    cout <<"enter ur age" ;
    cin>> age;

    if( age>14)

        {

                if (age>=18)
                 {
                cout<< "adult" ;
                  }


                else
                    {
                    cout <<"teenager";
                    }


          }

return0;

}























































the above program wont give any output for age less than 14...
for that, you will need another else statement.


4.Nested If-Else Statements

#include <iostream>
using namespace std;
int main ()

{
    int age;
    cout <<"enter ur age \n" ;
    cin>> age;

    if( age>=13)

        {
                    if (age>=18)
                     {
                    cout<< "adult" ;
                      }

                         else
                        {
                         cout <<"teenager";
                         }
          }


          else { cout<<"you are a kid";}

return 0;

}