Re: [Algorithms] How to get 3dvector largest coordinate index?

[Jason H. <jas...@di...>]

So, how about a "standard friendly" version of Pal-Kristian's template 
from a few days ago:

template<typename T, typename U>
static T bit_cast(const U val)
{
    union { U u; T t; } bits = { val }, secondBits;
    secondBits = bits;
    return secondBits.t;
}

    float x = 3.1415926f;
    uint32 asUint = bit_cast<uint32>(x);

Wouldn't this satisfy the standard?  There's no situation when 
secondBits is accessed as two types, only as a union.

JH

Gino van den Bergen wrote:
> My bad. It's the C99 standard, not the C++98 standard.
>
> "The following are unspecified: ... The value of a union member other 
> than the last one stored into (6.2.6.1)."
>
> liam mail wrote:
>   
>> 2009/3/6 Gino van den Bergen <gin...@gm... 
>> <mailto:gin...@gm...>>
>>
>>     Aliasing is having multiple references to the same memory location. 
>>
>>  
>>
>>     "Call me reckless but I just do not believe that
>>     strict-aliasing on union fields will be exploited by a C++
>>     compiler any
>>     time soon."
>>
>> Thank you I know what aliasing is, but as I said I do not see what 
>> this has to do with your comment as the standard guarantees the same 
>> space is in use.
>>
>>
>>     According to the C++ standard a compiler would be allowed to fetch
>>     pun.i
>>     before pun.f has been written 
>>
>>  
>>
>>     and the result would contain garbage
>>     instead of the bit-representation of x. 
>>
>>
>> Would you mind quoting or pointing me to the part of the standard 
>> which implies this.
>>
>> Liam
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>
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