﻿ C++ Exercises: Find the Authomorphic numbers between 1 to 1000 - w3resource

# C++ Exercises: Find the Authomorphic numbers between 1 to 1000

## C++ Numbers: Exercise-25 with Solution

Write a program in C++ to find the Authomorphic numbers between 1 to 1000.

Sample Solution:

C++ Code :

``````#include<iostream>
using namespace std;
bool chkAutomor(int num1)
{
int sqno = num1 * num1;
while (num1 > 0)
{
if (num1 % 10 != sqno % 10)
return false;
num1 /= 10;
sqno /= 10;
}
return true;
}
int main()
{
int i;
cout << "\n\n Find the the Authomorphic numbers between 1 to 1000 \n";
cout << " -------------------------------------------------------\n";
cout << " The Authomorphic numbers are: "<<endl;
for(i=1;i<=1000;i++)
{
if( chkAutomor(i))
cout << i<<" ";
}
cout<<endl;
}
``````

Sample Output:

```Find the the Authomorphic numbers between 1 to 1000
-------------------------------------------------------
The Authomorphic numbers are:
1 5 6 25 76 376 625
```

Flowchart:

C++ Code Editor:

What is the difficulty level of this exercise?

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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