Ralf W. Grosse-Kunstleve wrote:
Alexander Nasonov wrote:
Does it mean that your std library doesn't define compile-time contants in std::numeric_limits<T> ?
It does define std::numeric_limits<T>. Something more subtle must be wrong. How it compiles this?
#include <ios> #include <limits> #include <boost/config.hpp> #include <boost/integer_traits.hpp> #include <boost/static_assert.hpp> template<class T> struct lcast_precision { typedef std::numeric_limits<T> limits; BOOST_STATIC_CONSTANT(bool, use_default_precision = !limits::is_specialized || limits::is_exact ); BOOST_STATIC_CONSTANT(bool, is_specialized_bin = !use_default_precision && limits::radix == 2 && limits::digits > 0 ); BOOST_STATIC_CONSTANT(bool, is_specialized_dec = !use_default_precision && limits::radix == 10 && limits::digits10 > 0 ); BOOST_STATIC_CONSTANT(std::streamsize, streamsize_max = boost::integer_traits<std::streamsize>::const_max ); BOOST_STATIC_CONSTANT(unsigned int, precision_dec = limits::digits10 + 1U); BOOST_STATIC_ASSERT(!is_specialized_dec || precision_dec <= streamsize_max + 0UL ); BOOST_STATIC_CONSTANT(unsigned long, precision_bin = 2UL + limits::digits * 30103UL / 100000UL ); BOOST_STATIC_ASSERT(!is_specialized_bin || limits::digits + 0UL < ULONG_MAX / 30103UL && precision_bin > limits::digits10 + 0UL && precision_bin <= streamsize_max + 0UL ); BOOST_STATIC_CONSTANT(std::streamsize, value = is_specialized_bin ? precision_bin : is_specialized_dec ? precision_dec : 6 ); }; #include <iostream> int main() { std::cout << lcast_precision<float>::value << '\n'; std::cout << lcast_precision<double>::value << '\n'; //std::cout << lcast_precision<long double>::value << '\n'; } -- Alexander Nasonov Project Manager at Akmosoft ( http://www.akmosoft.com ) Blog: http://nasonov.blogspot.com Email: $(FirstName) dot $(LastName) at gmail dot com