Re: Program crashing on declaring large char array

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From	Ian Collins <ian-news@hotmail.com>
Newsgroups	comp.lang.c
Subject	Re: Program crashing on declaring large char array
Date	Sun, 18 Jun 2017 16:34:21 +1200
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On 06/18/17 04:11 PM, DFS wrote:
> I'm reading in a .csv file, counting the lines, and allocating arrays
> based on the line count.
>
> I want a multidimensional array of N rows (lines) by 5 columns.  I need
> each address in the array to store up to 25 characters.
>
> char data[lines][5][25];
>
> If the .csv file is small (few dozen lines) it works, but if the .csv
> file has 10,000 lines, it crashes.
>
> I assume it has something to do with memory allocation.

It doesn't have anything to do with memory allocation because you don't 
allocate any memory!

What is does show is you have exceed the stack size (let's assume there 
is a stack...) limit for your implementation.

> char data[lines][5][25] = malloc(lines * 5 * 25);  says 'Variable length
> array cannot be initialized'

Assuming "lines" isn't a compile time constant, you are creating a 
variable length array (VLA) which, as your compiler is happy to report, 
can not be initialised.

You need to allocate a block of rows, something like:

typedef char Row[5][25];

Row* data = malloc( lines * sizeof *stuff );

Then you can access the data by line.

-- 
Ian

Thread

Program crashing on declaring large char array DFS <nospam@dfs.com> - 2017-06-18 00:11 -0400
  Re: Program crashing on declaring large char array Ian Collins <ian-news@hotmail.com> - 2017-06-18 16:34 +1200
    Re: Program crashing on declaring large char array Ian Collins <ian-news@hotmail.com> - 2017-06-18 16:36 +1200
  Re: Program crashing on declaring large char array Barry Schwarz <schwarzb@dqel.com> - 2017-06-17 21:39 -0700
  Re: Program crashing on declaring large char array GOTHIER Nathan <nathan.gothier@gmail.com> - 2017-06-18 09:51 +0200
  Re: Program crashing on declaring large char array already5chosen@yahoo.com - 2017-06-18 03:49 -0700
    Re: Program crashing on declaring large char array already5chosen@yahoo.com - 2017-06-18 03:55 -0700
    Re: Program crashing on declaring large char array supercat@casperkitty.com - 2017-06-19 09:25 -0700
  Re: Program crashing on declaring large char array James Kuyper <jameskuyper@verizon.net> - 2017-06-18 14:10 -0400

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