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C++ Exercises: Check whether a given number is a perfect cube or not

C++ Numbers: Exercise-32 with Solution

Write a program in C++ to check whether a given number is a perfect cube or not.

Sample Solution:

C++ Code :

#include<iostream>
#include<math.h>
using namespace std;
int main() 
{ 
int num, curoot,ans; 

 cout << "\n\n Check whether a number is a perfect cube or not: \n";
 cout << " -----------------------------------------------------\n";
    cout<<" Input a number: ";
    cin>>num;
curoot=round(pow(num, 1.0/3.0));

if(curoot*curoot*curoot==num)
{
  cout<<" The number is a perfect Cube of "<<curoot<<endl;   
}
else
{
  cout<<" The number is not a perfect Cube."<<endl;   
}
}

Sample Output:

Check whether a number is a perfect cube or not:                      
 -----------------------------------------------------                 
 Input a number: 8                                                     
 The number is a perfect Cube of 2 

Flowchart:

Flowchart: Check whether a given number is a perfect cube or not

C++ Code Editor:

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Previous: Write a program in C++ to find circular prime numbers upto a specific limit.
Next: Write a program in C++ to display first 10 Fermat numbers.

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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