Print the sequence of all Odd numbers

#include<conio.h>

#include<iostream.h>

void main()

{

clrscr();

int a, b;

cout<<"Enter Starting Limit";

cin>>a;

cout<<"Enter ending Limit";

cin>>b;   

cout<<"All Odd Numbers Between "<<a<<" & "<<b<<" is\n";

while (a<=b)

{

if (a!=0 && a%2!=0)

cout<<a<<" ";

a++;

}

getch();

}

Output

Enter Starting Limit: 2

Enter ending Limit: 10

All Even Numbers Between 2 & 10 is

3 5 7 9

Print the sequence of all Even numbers

#include<conio.h>

#include<iostream.h>

void main()

{                

   clrscr();

   int a, b;

   cout<<"Enter Starting Limit: ";

   cin>>a;

   cout<<"Enter ending Limit: ";

   cin>>b;

   cout<<"All Even Numbers Between "<<a<<" & "<<b<<" is\n";

   while (a<=b)

{

if (a!=0 && a%2==0)

cout<<a<<" ";

a++;

}

   getch();

}

Output

Enter Starting Limit: 3

Enter ending Limit: 17

All Even Numbers Between 3 & 17 is

4 6 8 10 12 14 16

Program to find perfect number

What is a perfect number?

"Perfect number is a positive number which sum of all positive divisors excluding that number." 

For example 6 is Perfect Number since divisor of 6 are 1, 2 and 3. Sum of its divisor is

1 + 2+ 3 =6

and  28 is also a Perfect Number

 since 1+ 2 + 4 + 7 + 14= 28

Other perfect numbers: 496, 8128

CODE FOR PERFECT NUMBER IN C++

1. #include<iostream.h
2. #include<conio.h>
3. void main()                 //Start of main
4. {
5.   clrscr();
6.    int i=1, u=1, sum=0;
7.    while(i<=500)
8.  {                                  // start of first loop.
9.    while(u<=500)
10.    {                               //start of second loop.
11.      if(u<i)
12.      {
13.       if(i%u==0 )
14.       sum=sum+u;
15.      }                          //End of if statement
16.      u++;
17.    }                           //End of second loop
18.    if(sum==i)
19.    {
20.     cout<<i<<" is a perfect number."<<"\n";
21.    }
22.    i++;
23.    u=1;  sum=0;
24.  }                             //End of First loop
25.    getch();
26.  }

 Sample output

6 is a perfect number.

28 is a perfect number.

496 is a perfect number.

Note:

If you want to calculate perfect number within your desire limit simply take a variable and replaced 500 with it.