Re: No math constants in the C++ standard?
* Thomas Richter:
Rune Allnor schrieb:
So: Why was M_PI (or some similar constant) excluded
from the standard? As I understand, it was excluded from
the C standard as well.
Since when is M_PI *not* part of the C++ standard? It is part of cmath,
which is part of the C++ standard library???
#include <cmath>
#include <cstdio>
int main(int argc,char **argv)
{
printf("%g\n",M_PI);
return 0;
}
{ Mod factoid: M_PI has never been part of either the C or C++
standards. -mod }
<with-different-hat-on>
Just adding to the helpful mod's comment:
M_PI & friends appear to be part of the current Posix standard as an XSI
(X/Open
System Interfaces) extension, "Application developers may confidently make
use
of such extensions on all systems supporting the X/Open System Interfaces
option":
<url: http://www.opengroup.org/onlinepubs/9699919799/basedefs/math.h.html>.
M_PI is also available with Visual C++ for Windows.
However, for the g++ compiler, "If strict ISO and/or POSIX compliance are
requested [M_PI] is not defined",
<url: http://www.gnu.org/s/libc/manual/html_node/Trig-Functions.html>.
Cheers & hth.,
- Alf
</with-different-hat-on>
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