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Re: Allocate length of word vs fixed length

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On 19/07/2021 23:21, dfs wrote:
> On 7/19/21 3:46 PM, Stefan Ram wrote:
>> dfs <nospam@dfs.com> writes:
>>> Also, does anyone have any 'tricks' to make such a file load routine
>>> faster/more efficient?  Thanks
>>
>>    A lot depends on what you then want to do with those words.
>>
>>    If they are not to be modified, but just to be read later,
>>    you can read the whole file into one region of memory
>>    and then write a NUL character after each word.
> 
> They're just to be read and pattern-matched against.
> 
> 
>>    If you need to do some per-word processing while reading,
>>    you can still allocate one large region of memory and
>>    append each word to it.
>>
>>>     char **words = malloc(sizeof(char*) * lines);
>>
>>    I assume that you have your reasons for not checking
>>    the result of malloc here.
> 
> 
> Program is for me only.
> 
> I just tested:
> lines = 2000000000;
> char **words = malloc(sizeof(char*) * lines);
> if(words == NULL)
> {
>    printf("malloc failed\n");
>    exit(0);
> }
> 
> and it failed and exited.

Is this a 32-bit system? Or a 32-bit compiler on a 64-bit system?

If so, the largest allocation size might be 2GB, and your request was 
for 8GB.

On a 64-bit system, you might be less lucky, and malloc won't fail even 
if the allocation exceeds physical memory. It'll just get very slow.

Then there's little point in checking the malloc result.

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Allocate length of word vs fixed length dfs <nospam@dfs.com> - 2021-07-19 12:50 -0400
  Re: Allocate length of word vs fixed length Bart <bc@freeuk.com> - 2021-07-19 19:01 +0100
    Re: Allocate length of word vs fixed length dfs <nospam@dfs.com> - 2021-07-19 14:29 -0400
      Re: Allocate length of word vs fixed length Bart <bc@freeuk.com> - 2021-07-19 19:49 +0100
        Re: Allocate length of word vs fixed length dfs <nospam@dfs.com> - 2021-07-19 18:01 -0400
          Re: Allocate length of word vs fixed length Bart <bc@freeuk.com> - 2021-07-19 23:25 +0100
      Re: Allocate length of word vs fixed length scott@slp53.sl.home (Scott Lurndal) - 2021-07-19 20:00 +0000
        Re: Allocate length of word vs fixed length Branimir Maksimovic <branimir.maksimovic@gmail.com> - 2021-07-19 23:29 +0000
      Re: Allocate length of word vs fixed length Real Troll <real.troll@trolls.com> - 2021-07-20 00:30 +0100
        Re: Allocate length of word vs fixed length DFS <nospam@dfs.com> - 2021-07-19 20:40 -0400
          Re: Allocate length of word vs fixed length Real Troll <real.troll@trolls.com> - 2021-07-20 17:00 +0000
      Re: Allocate length of word vs fixed length Kaz Kylheku <563-365-8930@kylheku.com> - 2021-07-24 01:07 +0000
  Re: Allocate length of word vs fixed length David Brown <david.brown@hesbynett.no> - 2021-07-19 21:35 +0200
    Re: Allocate length of word vs fixed length dfs <nospam@dfs.com> - 2021-07-19 18:02 -0400
  Re: Allocate length of word vs fixed length Ike Naar <ike@rie.sdf.org> - 2021-07-19 21:11 +0000
    Re: Allocate length of word vs fixed length dfs <nospam@dfs.com> - 2021-07-19 18:03 -0400
      Re: Allocate length of word vs fixed length Ike Naar <ike@sdf.org> - 2021-07-20 05:28 +0000
  Re: Allocate length of word vs fixed length dfs <nospam@dfs.com> - 2021-07-19 18:21 -0400
    Re: Allocate length of word vs fixed length Bart <bc@freeuk.com> - 2021-07-19 23:29 +0100
      Re: Allocate length of word vs fixed length dfs <nospam@dfs.com> - 2021-07-19 18:40 -0400
  Re: Allocate length of word vs fixed length Peter 'Shaggy' Haywood <phaywood@alphalink.com.au> - 2021-07-20 11:44 +1000
  Re: Allocate length of word vs fixed length Real Troll <real.troll@trolls.com> - 2021-07-20 22:15 +0000
    Re: Allocate length of word vs fixed length dfs <nospam@dfs.com> - 2021-07-20 20:22 -0400
      Re: Allocate length of word vs fixed length dfs <nospam@dfs.com> - 2021-07-21 23:23 -0400

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