How do I convert between big-endian and little-endian values in C++?

Question

How do I convert between big-endian and little-endian values in C++?

EDIT: For clarity, I have to translate binary data (double-precision floating point values and 3

Answer 1

Most platforms have a system header file that provides efficient byteswap functions. On Linux it is in . You can wrap it nicely in C++:

#include 

#include 

template struct SizeT {};

#define BYTESWAPS(bits) \
template inline T htobe(T t, SizeT) { return htobe ## bits(t); } \
template inline T htole(T t, SizeT) { return htole ## bits(t); } \
template inline T betoh(T t, SizeT) { return be ## bits ## toh(t); } \
template inline T letoh(T t, SizeT) { return le ## bits ## toh(t); }

BYTESWAPS(16)
BYTESWAPS(32)
BYTESWAPS(64)

#undef BYTESWAPS

template inline T htobe(T t) { return htobe(t, SizeT()); }
template inline T htole(T t) { return htole(t, SizeT()); }
template inline T betoh(T t) { return betoh(t, SizeT()); }
template inline T letoh(T t) { return letoh(t, SizeT()); }

int main()
{
    std::cout << std::hex;
    std::cout << htobe(static_cast(0xfeca)) << '\n';
    std::cout << htobe(0xafbeadde) << '\n';

    // Use ULL suffix to specify integer constant as unsigned long long 
    std::cout << htobe(0xfecaefbeafdeedfeULL) << '\n';
}

Output:

cafe
deadbeaf
feeddeafbeefcafe