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C++ Exercises: Display first 10 Fermat numbers

C++ Numbers: Exercise-33 with Solution

Write a program in C++ to display first 10 Fermat numbers.

Sample Solution:

C++ Code :

# include <iostream>
# include <math.h>
using namespace std;
int main()
{
    int n=0;
	double result;
 cout << "\n\n Display first 10 Fermat numbers:\n";
 cout << "-------------------------------------\n";
cout << " The first 10 Fermat numbers are: "<<endl;
while (n <= 10) 
		{
            result= pow(2, pow(2, n)) + 1;
            n++;
            cout << result << endl;
        }
}

Sample Output:

 Display first 10 Fermat numbers:                                      
-------------------------------------                                  
 The first 10 Fermat numbers are:                                      
3                                                                      
5                                                                      
17                                                                     
257                                                                    
65537                                                                  
4.29497e+09                                                            
1.84467e+19                                                            
3.40282e+38                                                            
1.15792e+77                                                            
1.34078e+154                                                           
inf      

Flowchart:

Flowchart: Display first 10 Fermat numbers

C++ Code Editor:

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Next: Write a program in C++ to find any number between 1 and n that can be expressed as the sum of two cubes in two (or more) different ways.

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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