On Thu, 3 Aug 2006 11:35:19 +0100, "John Maddock" <john@johnmaddock.co.uk> wrote:
And the endianness of the float's if you're doing bit testing.
Which shouldn't be a problem for you ;-) Or just position/bitmask of the sign bit.
But of course if there is a macro already it's easy enough to convert it into a function.
Yep. Even if no macro exists you can perhaps hide the machine-dependent stuff in one single "low-level primitive" function upon which you can build all (or much of) the rest. I'm thinking to something like // your namespace... enum type { finite, zero, nan, inf }; template <typename T> type get_type(T t); Also you could probably automatically generate much of the system dependent stuff, for the most common systems. For instance: // widely (not completely) portable void calculate() { typedef float T; // for instance typedef unsigned char byte; T plus_1 ( 1 ); T minus_1( -1 ); const volatile byte * b_plus = reinterpret_cast<const volatile byte *>(&plus_1); const volatile byte * b_minus = reinterpret_cast<const volatile byte *>(&minus_1); int i = 0; int bit = 0; bool found = false; for (i = 0; i < sizeof( T ); ++i ) { for (bit = 0; bit < CHAR_BIT; ++bit) { const int mask = 1 << bit; if( (b_plus[i] & mask) != (b_minus[i] & mask) ) { assert(found == false); found = true; } } } assert(found == true); std::cout << "sign bit at byte " << (i-1) <<", bit " << (bit-1) << '\n' ; } Ok, that will never compile but should give the idea. If any of the asserts triggers just pretend nothing happened, calmly shut the computer down and do not walk... run! -- [ Gennaro Prota, C++ developer for hire ]