Atila Neves: "C IS NOT MAGICALLY FAST, PART 2"

Atila Neves via Digitalmars-d digitalmars-d at puremagic.com
Tue Jul 19 08:40:03 PDT 2016


On Tuesday, 19 July 2016 at 10:39:26 UTC, Jakob Bornecrantz wrote:
> On Tuesday, 19 July 2016 at 10:07:11 UTC, Atila Neves wrote:
>> On Tuesday, 19 July 2016 at 02:54:37 UTC, Saurabh Das wrote:
>>>
>>> Posted on Atila's blog yesterday:
>>>
>>> https://atilanevesoncode.wordpress.com/2016/07/18/c-is-not-magically-fast-part-2/
>>
>> So, about D vs C++ there... last night for reasons I forget I 
>> tried replacing std::string with const char* in the C++ 
>> version, and then it got faster than D. I don't know why.
>>
>> At first I thought std::string was being copied instead of 
>> being moved, but some static_asserts made me doubt that. 
>> Either way, there's no good reason I can think of for C++ to 
>> magically speed up for const char*. Hmm :(
>>
>> Atila
>
> What is the sizeof(Foo) for all of the cases?

C and C++ const char*: 16
C++ std::string: 64
D: 24

>
> What does "charPtr < charPtr" do in C++ compared to std::string?

I used strcmp for const char* in C++.

Atila




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