Has truth of arrays always acted like this?

[Bill Baxter]

> "Mike Parker" <aldacron71 at yahoo.com> wrote in message 
> news:feuj8s$1kjt$1 at digitalmars.com...
>> Bill Baxter wrote:
>>> Bill Baxter wrote:
>>>> I could have sworn there was a big discussion just recently about how 
>>>> "null" and "empty" were the same thing with D arrays and some people 
>>>> were arguing that should change.  But at least with the most recent D 
>>>> v1.022, it seems the truth value of uninitialized and empty arrays *are* 
>>>> different.  Has it always been that way?
>>> I think maybe the discussion I was remembering was about comparison with 
>>> null.  Indeed (a==null) is true for both uninitialized *and* length==0 
>>> arrays.
>>>
>>> That seems completely backwards to me.  If anything, a==null should be 
>>> the one that checks if a has a buffer allocated at all, and if(a) should 
>>> be the one that checks for any form of emptiness.
>>>
>>> Barring that, they should just behave the same.
>>>
>>> --bb
>> I recall a recent discussion specifically about empty vs. null strings, 
>> i.e. an empty string ("") is equivalent to a null string:
>>
>> char[] s1 = "";
>> char[] s2 = null;
>>
>> if(s1 == s2) writefln("equal");
>>
>> This will evaluate to true. 
> 

Kris wrote:
 > Well, I sure hope that /never/ happens. A null is a null (the array 
.ptr and
 > .length are both zero), while an empty string is perfectly valid.

Hope what never happens?

 > tip: faster way (on 32bit platforms) to check for null array is to 
test the
 > .ptr only, since it's 32 bits rather than 64.

size_t is 32 bits on a 32 bit platform too.

--bb