memory allocation for two dimensional array

[John Hanley]

I need to allocate memory dynamically for a two dimensional array. It's
basically a pointer to an array of 2 element arrays: I declared it as long
int ** arr. The number of two element arrays are unknown at compile time.

I am not quite sure if I allocated memory properly for this (I am sure I
didn't).

arr = malloc((sizeof( long int)*2)*number_ of_elements)

when I debug it, I have access to arr[0][0], arr[1][0], arr[2][0], etc...
but not arr[0][1]. It tells me it can't access memory which leads me to
believe I don't quite have my memory allocation and/or declaration correct.

I have tried a few different ways, but I obviously haven't found the right
way to do it yet.

Any suggestions?

Thanks a bunch!

John

[Ravi Uday]

Re: memory allocation for two dimensional array


"John Hanley" <jdhanley@telus planet.net> wrote in message
news:1091416554 .601966@proxy2. srv.ualberta.ca ...[color=blue]
> I need to allocate memory dynamically for a two dimensional array. It's
> basically a pointer to an array of 2 element arrays: I declared it as[/color]
long[color=blue]
> int ** arr. The number of two element arrays are unknown at compile time.
>
> I am not quite sure if I allocated memory properly for this (I am sure I
> didn't).
>
> arr = malloc((sizeof( long int)*2)*number_ of_elements)
>[/color]
Have you tried looking into C-FAQ section.
Allocating 2D arrays are nicely discussed there

- Ravi

[Emmanuel Delahaye]

Re: memory allocation for two dimensional array

John Hanley wrote on 02/08/04 :[color=blue]
> I need to allocate memory dynamically for a two dimensional array.[/color]


It's a FAQ.

--
Emmanuel
The C-FAQ: http://www.eskimo.com/~scs/C-faq/faq.html

"C is a sharp tool"