Array.copy

[Alan Mosley]

I have a multi dimensional array, I want to copy, but when I do It shows 0's
in the second dimension.

Can I copy a multi dimensional array?

if so how do i do it.

Thanks

[Peter Duniho]

On Mon, 28 Jul 2008 21:15:47 -0700, Alan Mosley <me@workwrote:

I have a multi dimensional array, I want to copy, but when I do It shows
0's
in the second dimension.

Can I copy a multi dimensional array?

Yes.

if so how do i do it.

You need to copy each sub-array individually. In Java, a
"multi-dimensional" array is really just an array of arrays.

Pete

[privatenews.microsoft.com]

Hi Alan,

Here's an example:

int[,] nums = { { 1, 2 }, { 3, 4 } };

int[,] numsCopy = new int[nums.GetUpperBound(0) + 1,
nums.GetUpperBound(1) + 1];

for (int i = 0; i <= nums.GetUpperBound(0); i++)
{
for (int j = 0; j <= nums.GetUpperBound(1); j++)
{
numsCopy[i, j] = nums[i, j];
Console.WriteLine("numsCopy[{0},{1}]: {2}", i, j,
numsCopy[i, j]);
}
}

Joe
http://www.csharp-station.com

"Alan Mosley" <me@workwrote in message
news:e1**************@TK2MSFTNGP03.phx.gbl...

>I have a multi dimensional array, I want to copy, but when I do It shows
0's in the second dimension.

Can I copy a multi dimensional array?

if so how do i do it.

Thanks

[Peter Duniho]

On Mon, 28 Jul 2008 21:39:08 -0700, Peter Duniho
<Np*********@nnowslpianmk.comwrote:

[...]
You need to copy each sub-array individually. In Java, a
"multi-dimensional" array is really just an array of arrays.

Sigh...sorry. In the middle of a Java program, and got confused about
what newsgroup I'm in. :)

Anyway, C# does support true "multi-dimensional" arrays. However, it also
supports "jagged" arrays, which are arrays of arrays. So, depending on
how you created your multi-dimensional array, you might in fact have to
copy each sub-array individually as I wrote.

If you have a true multi-dimensional array, then you can use Array.Copy(),
which will treat your multi-dimensional array as one long array (which it
is really is :) ). In that case, the length you'll want to pass for the
Copy() method would be the total number of elements you want copied over
all dimensions. For example, if you have a 10x10 array, you'd pass a
length of 100 to copy all elements from one array to the other.

I apologize for the confusion.

Pete

[Peter Duniho]

On Mon, 28 Jul 2008 21:50:53 -0700, privatenews.microsoft.com
<jm***@csharp-stat10n.comwrote:

Hi Alan,

Here's an example:

int[,] nums = { { 1, 2 }, { 3, 4 } };

int[,] numsCopy = new int[nums.GetUpperBound(0) + 1,
nums.GetUpperBound(1) + 1];

for (int i = 0; i <= nums.GetUpperBound(0); i++)
{
for (int j = 0; j <= nums.GetUpperBound(1); j++)
{
numsCopy[i, j] = nums[i, j];
Console.WriteLine("numsCopy[{0},{1}]: {2}", i, j,
numsCopy[i, j]);
}
}

Actually, the above can be shorted to:

int[,] numsCopy = new int[nums.GetLength(0), nums.GetLength(1)];

Array.Copy(nums, numsCopy, nums.GetLength(0) * nums.GetLength(1));

Note also the use of GetLength() instead of GetUpperBound(). This not
only accounts for situations where the lower bound isn't 0, but also
avoids the need to adjust the upper bound by 1 even when the lower bound
is 0. :)

Pete

[ThatsIT.net.au]

"Peter Duniho" <Np*********@nnowslpianmk.comwrote in message
news:op***************@petes-computer.local...

On Mon, 28 Jul 2008 21:39:08 -0700, Peter Duniho
<Np*********@nnowslpianmk.comwrote:

>[...]
You need to copy each sub-array individually. In Java, a
"multi-dimensional" array is really just an array of arrays.

Sigh...sorry. In the middle of a Java program, and got confused about
what newsgroup I'm in. :)

Anyway, C# does support true "multi-dimensional" arrays. However, it also
supports "jagged" arrays, which are arrays of arrays. So, depending on
how you created your multi-dimensional array, you might in fact have to
copy each sub-array individually as I wrote.

If you have a true multi-dimensional array, then you can use Array.Copy(),
which will treat your multi-dimensional array as one long array (which it
is really is :) ). In that case, the length you'll want to pass for the
Copy() method would be the total number of elements you want copied over
all dimensions. For example, if you have a 10x10 array, you'd pass a
length of 100 to copy all elements from one array to the other.

I apologize for the confusion.

Pete

thanks ill try that

[ThatsIT.net.au]

"Peter Duniho" <Np*********@nnowslpianmk.comwrote in message
news:op***************@petes-computer.local...

On Mon, 28 Jul 2008 21:50:53 -0700, privatenews.microsoft.com
<jm***@csharp-stat10n.comwrote:

>Hi Alan,

Here's an example:

int[,] nums = { { 1, 2 }, { 3, 4 } };

int[,] numsCopy = new int[nums.GetUpperBound(0) + 1,
nums.GetUpperBound(1) + 1];

for (int i = 0; i <= nums.GetUpperBound(0); i++)
{
for (int j = 0; j <= nums.GetUpperBound(1); j++)
{
numsCopy[i, j] = nums[i, j];
Console.WriteLine("numsCopy[{0},{1}]: {2}", i, j,
numsCopy[i, j]);
}
}

Actually, the above can be shorted to:

int[,] numsCopy = new int[nums.GetLength(0), nums.GetLength(1)];

Array.Copy(nums, numsCopy, nums.GetLength(0) * nums.GetLength(1));

Note also the use of GetLength() instead of GetUpperBound(). This not
only accounts for situations where the lower bound isn't 0, but also
avoids the need to adjust the upper bound by 1 even when the lower bound
is 0. :)

Pete

thanks
I'll will give it a try tomorrow

[Alan Mosley]

Peter I should of made myself clear, i want to inlarge the array.

Im trying to do as i would in VB using redim preserve
"Peter Duniho" <Np*********@nnowslpianmk.comwrote in message
news:op***************@petes-computer.local...

On Mon, 28 Jul 2008 21:50:53 -0700, privatenews.microsoft.com
<jm***@csharp-stat10n.comwrote:

>Hi Alan,

Here's an example:

int[,] nums = { { 1, 2 }, { 3, 4 } };

int[,] numsCopy = new int[nums.GetUpperBound(0) + 1,
nums.GetUpperBound(1) + 1];

for (int i = 0; i <= nums.GetUpperBound(0); i++)
{
for (int j = 0; j <= nums.GetUpperBound(1); j++)
{
numsCopy[i, j] = nums[i, j];
Console.WriteLine("numsCopy[{0},{1}]: {2}", i, j,
numsCopy[i, j]);
}
}

Actually, the above can be shorted to:

int[,] numsCopy = new int[nums.GetLength(0), nums.GetLength(1)];

Array.Copy(nums, numsCopy, nums.GetLength(0) * nums.GetLength(1));

Note also the use of GetLength() instead of GetUpperBound(). This not
only accounts for situations where the lower bound isn't 0, but also
avoids the need to adjust the upper bound by 1 even when the lower bound
is 0. :)

Pete

[Peter Duniho]

On Wed, 30 Jul 2008 19:10:12 -0700, Alan Mosley <me@workwrote:

Peter I should of made myself clear, i want to inlarge the array.

Im trying to do as i would in VB using redim preserve

I don't understand your follow-up at all. It's completely different from
the original question.

That said, C# won't allow you to reallocate an array in-place. You have
to create a new one and copy the elements.

Depending on which dimension(s) you are changing, you might still be able
to get away with using the Array.Copy() method. But I wouldn't bother
unless you really had a serious performance issue that needed to be
addressed. Otherwise, just copy each element explicitly. If you fix
Joe's code so that it's using the correct lower and upper bound as
appropriate to your actual arrays, then it'd be as simple as code like his
and then assigning the temporary destination array reference back to your
original when you're done.

Pete

[=?ISO-8859-1?Q?Arne_Vajh=F8j?=]

Alan Mosley wrote:

Peter I should of made myself clear, i want to inlarge the array.

Im trying to do as i would in VB using redim preserve

In .NET 3.5 you have the Resize. In older version you have
top new and Copy. Note that Resize also copies - it just hides
the fact from you.

Code snippet:

int[] ia = { 1, 2, 3 };
foreach(int iv in ia)
{
Console.WriteLine(iv);
}
// old way:
int[] ia2 = new int[4];
ia.CopyTo(ia2, 0);
ia2[3] = 4;
foreach(int iv in ia2)
{
Console.WriteLine(iv);
}
// .NET 3.5 way
Array.Resize(ref ia, 4);
ia[3] = 4;
foreach(int iv in ia2)
{
Console.WriteLine(iv);
}
Arne

[ThatsIT.net.au]

sorry I did not get back for such a long time, I sorted the problem another
way, but still would like to know a better way.
I seen your example but I was trying to resize a multidimensional array.

"Arne Vajhøj" <ar**@vajhoej.dkwrote in message
news:48***********************@news.sunsite.dk...

Alan Mosley wrote:

Peter I should of made myself clear, i want to inlarge the array.

Im trying to do as i would in VB using redim preserve

In .NET 3.5 you have the Resize. In older version you have
top new and Copy. Note that Resize also copies - it just hides
the fact from you.

Code snippet:

int[] ia = { 1, 2, 3 };
foreach(int iv in ia)
{
Console.WriteLine(iv);
}
// old way:
int[] ia2 = new int[4];
ia.CopyTo(ia2, 0);
ia2[3] = 4;
foreach(int iv in ia2)
{
Console.WriteLine(iv);
}
// .NET 3.5 way
Array.Resize(ref ia, 4);
ia[3] = 4;
foreach(int iv in ia2)
{
Console.WriteLine(iv);
}
Arne