how to get exact value of pi in c and c++

 Value of pi can be defined as  a macro in c or it can be declared as constant division.

it can be determined without learning it . if you search on google , you will get  value of pi

but it so big that you can't remember it.

let's see. 

consider the computer program :

#include<iostream>

using namespace std;

#define pi 3.141593                         // you must remember it for this methord 

int main()

{

   cout << "area of circle of radius 3 is " << pi*3*3;

   return 0;

}

Another methord (best methord ):

#include<iostream>

using namespace std;

const double pi = 22.0/7.0          // you does not have to remember it now 

int main()

{

   cout << "area of circle of radius 3 is " << pi*3*3;

   return 0;

}

refrences:

https://www.quantstart.com/articles/Mathematical-Constants-in-C/

https://stackoverflow.com/questions/1727881/how-to-use-the-pi-constant-in-c

https://www.geeksforgeeks.org/pi-in-c-with-examples/