round and M_PI

[JustSomeGuy]

In MS Visual C++ 6.0

Where is M_PI defined?
Where is round defined?

 

[Rob Williscroft]

JustSomeGuy wrote in @news3.calgary.shaw.ca:

In MS Visual C++ 6.0

Where is M_PI defined?
Where is round defined?

They are not defined in standard C++, If you need to know about
Visual C++ ask in one of the ms newsgroups, or do this:

#include <iostream>
#include <ostream>
#include <iomanip>
#include <cmath>
#include <limits>

double const m_pi = 2 * acos(0.0);

inline double round( double d )
{
return floor( d + 0.5 );
}

int main()
{
using namespace std;

cout << setprecision( numeric_limits< double >::digits10 );

cout << m_pi << endl;

cout << floor( m_pi ) << endl;
cout << floor( -m_pi ) << endl;

cout << ceil( m_pi ) << endl;
cout << ceil( -m_pi ) << endl;

cout << round( m_pi ) << endl;
cout << round( -m_pi ) << endl;
}

HTH


Rob.

 

[PT]

In MS Visual C++ 6.0

Where is M_PI defined?

Sorry, I use g++, not MS Visual C++, but maybe I can still be useful...

At my system, M_PI is not defined as such (it doesn't have any memory
associated with it), it's just a macro declared (#define'd) in math.h.

Where is round defined?

round is also declared in math.h (it has a prototype there), but it's
defined somewhere in the maths library (I don't know exactly, which one do
you have).

 

[Victor Bazarov]

Sorry, I use g++, not MS Visual C++, but maybe I can still be useful...

At my system, M_PI is not defined as such (it doesn't have any memory
associated with it), it's just a macro declared (#define'd) in math.h.


round is also declared in math.h (it has a prototype there), but it's
defined somewhere in the maths library (I don't know exactly, which one do
you have).

Neither of the names in the subject line is standard. Not that
it can't be found on your system, just that it's not necessarily
there.

Victor

 

[Pete Becker]

Neither of the names in the subject line is standard.

To expand a bit: round is not standard C++, but it's standard C, having
been added in C99.

 

[JustSomeGuy]

Must be that Micro$oft decided that PI wasn't object oriented, and that no
one would need a rounding method.