Re: [PATCH 3/6] string: reduce strjoin runtime, drop trailing separator

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 27.10.22 09:33, Sascha Hauer wrote:
> On Thu, Oct 27, 2022 at 09:24:20AM +0200, Ahmad Fatoum wrote:
>> Hi,
>>
>> On 27.10.22 08:56, Sascha Hauer wrote:
>>> On Wed, Oct 26, 2022 at 08:42:02AM +0200, Ahmad Fatoum wrote:
>>>> The implementation of strjoin is a bit suboptimal. The destination
>>>> string is traversed from the beginning due to strcat and we have a
>>>> left-over separator at the end, while it should only be in-between.
>>>>
>>>> Fix this.
>>>
>>> Rather than fixing a just introduced function I would expect a patch
>>> introducing strjoin() and then another one converting the time command
>>> over to use it.
>>
>> What difference does it make?
> 
> You wouldn't have to fixup code you just introduced.

The alternative of changing stuff just to shift it around directly after
doesn't sound that much more appealing, but I can do that anyway.

> 
>>>
>>> 	for (i = 0; i < arrlen; i++) {
>>> 		p = stpcpy(p, arr[i]);
>>> 		if (i < arrlen - 1)
>>> 			p = stpcpy(p, separator);
>>> 	}
>>>
>>> That would also allow you to optimize the allocated buffer size above.
>>
>> I like my version more. I dislike these once-only checks inside loops.
> 
> No problem ;)
> 
> 	for (i = 0; i < arrlen - 1; i++) {
> 		p = stpcpy(p, arr[i]);
> 		p = stpcpy(p, separator);
> 	}
> 
> 	stpcpy(p, arr[i]);

I can do that, albeit with mempcpy. I already got separatorlen.

Cheers,
Ahmad

> 
> Sascha
> 


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