w3resource

C++ Exercises: Find Perfect numbers and number of Perfect numbers between 1 to 1000

C++ Numbers: Exercise-5 with Solution

Write a program in C++ to find Perfect numbers and number of Perfect numbers between 1 to 1000.

Pictorial Presentation:

C++ Exercises: Find Perfect numbers and number of Perfect numbers between 1 to 1000

Sample Solution:

C++ Code :

# include <iostream>
# include <string>
using namespace std;
int main()
{
    int i=1, u=1, sum=0,ctr=0;
 cout << "\n\n Find the Perfect numbers and number of Perfect numbers between 1 to 1000:\n";
 cout << "------------------------------------------------------------------------------\n";
cout << "The Perfect numbers are : \n";
   while(i<=1000)
 {                                 
   while(u<=1000)
   {                              
     if(u<i)
     {
      if(i%u==0 )
      sum=sum+u;
     }                         
     u++;
   }                           
   if(sum==i)
   {
       ctr++;
    cout<<i<<" is a Perfect number."<<"\n";
   }
   i++;
   u=1;  sum=0;
 } 
     cout<<"Number of Perfect numbers between 1 to 1000 is: "<<ctr<<"\n";
}

Sample Output:

 Find the Perfect numbers and number of Perfect numbers between 1 to 1000:                                                                    
------------------------------------------------------------------------------                                                                
The Perfect numbers are :                                              
6 is a perfect number.                                                 
28 is a perfect number.                                                
496 is a perfect number.                                               
Number of perfect numbers between 1 to 1000 is: 3 

Flowchart:

Flowchart: Find Perfect numbers and number of Perfect numbers between 1 to 1000

C++ Code Editor:

Contribute your code and comments through Disqus.

Previous: Write a program in C++ to check whether a given number is Perfect or not.
Next: Write a program in C++ to check whether a given number is Deficient or not.

What is the difficulty level of this exercise?



Share this Tutorial / Exercise on : Facebook and Twitter

C++ Programming: Tips of the Day

How to use the PI constant in C++?

On some (especially older) platforms (see the comments below) you might need to

#define _USE_MATH_DEFINES and then include the necessary header file:
#include<math.h>

and the value of pi can be accessed via:

M_PI

In math.h (2014) it is defined as:

# define M_PI           3.14159265358979323846  /* pi */

but check your math.h for more. An extract from the "old" math.h (in 2009):

/* Define _USE_MATH_DEFINES before including math.h to expose these macro
 * definitions for common math constants.  These are placed under an #ifdef 
 * since these commonly-defined names are not part of the C/C++ standards.
 */

However:

  1. on newer platforms (at least on my 64 bit Ubuntu 14.04) I do not need to define the _USE_MATH_DEFINES
  2. On (recent) Linux platforms there are long double values too provided as a GNU Extension:
# define M_PIl          3.14159265358979323846

Ref: https://bit.ly/3G4BgzQ