How can I reset a rectangualr array without having to loop through it?

int[][] myRectData = new int[][](10,10);

myRectData.length = 0;
myRectData[].length = 0;		
myRectData[][].length = 0;	

They all give: slice expression .. is not a modifiable lvalue.

-- 
Robert M. Münch
http://www.saphirion.com
smarter | better | faster

On Saturday, 25 May 2019 at 14:28:24 UTC, Robert M. Münch wrote:
> How can I reset a rectangualr array without having to loop through it?
>
> int[][] myRectData = new int[][](10,10);
>
> myRectData.length = 0;
> myRectData[].length = 0;		
> myRectData[][].length = 0;	
>
> They all give: slice expression .. is not a modifiable lvalue.

This works form me:

//DMD64 D Compiler 2.072.2
import std.stdio;

void main()
{
    auto arr = new int[][](10,10);
    writeln(arr.length);
    arr.length=0;
    writeln(arr.length);
}

output:
10
0

Matheus.

On 2019-05-25 14:28:24 +0000, Robert M. Münch said:

> How can I reset a rectangualr array without having to loop through it?
> 
> int[][] myRectData = new int[][](10,10);
> 
> myRectData.length = 0;
> myRectData[].length = 0;		
> myRectData[][].length = 0;	
> 
> They all give: slice expression .. is not a modifiable lvalue.

My question was unprecise: I want to keep the first dimension and only reset the arrays of the 2nd dimension. So that I can append stuff again.

-- 
Robert M. Münch
http://www.saphirion.com
smarter | better | faster

On Saturday, 25 May 2019 at 16:17:40 UTC, Robert M. Münch wrote:
> On 2019-05-25 14:28:24 +0000, Robert M. Münch said:
>
>> How can I reset a rectangualr array without having to loop through it?
>> 
>> int[][] myRectData = new int[][](10,10);
>> 
>> myRectData.length = 0;
>> myRectData[].length = 0;		
>> myRectData[][].length = 0;	
>> 
>> They all give: slice expression .. is not a modifiable lvalue.
>
> My question was unprecise: I want to keep the first dimension and only reset the arrays of the 2nd dimension. So that I can append stuff again.

myRectData[] = null;

On 2019-05-28 01:52:28 +0000, 9il said:

> myRectData[] = null;

:-/ Ok... doesn't look to complicated ;-) Still learning a lot about D...

-- 
Robert M. Münch
http://www.saphirion.com
smarter | better | faster

On 5/28/19 4:58 PM, Robert M. Münch wrote:
> On 2019-05-28 01:52:28 +0000, 9il said:
> 
>> myRectData[] = null;
> 
> :-/ Ok... doesn't look to complicated ;-) Still learning a lot about D...
> 

Keep in mind, this does not reuse the allocated arrays, it simply resets them to point at nothing (and will need to be reallocated).

To reset the way you want, you need a loop:

foreach(ref arr; myRectData)
{
   arr.length = 0;
   arr.assumeSafeAppend;
}

-Steve