float bits and strict aliasing

Question

I am trying to extract the bits from a float without invoking undefined behavior. Here is my first attempt:

unsigned foo(float x)
{
    unsigned* u = (unsign         


        

Answer 1

About the only way to truly avoid any issues is to memcpy.

unsigned int FloatToInt( float f )
{
   static_assert( sizeof( float ) == sizeof( unsigned int ), "Sizes must match" );
   unsigned int ret;
   memcpy( &ret, &f, sizeof( float ) );
   return ret;
}

Because you are memcpying a fixed amount the compiler will optimise it out.

That said the union method is VERY widely supported.