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Dynamic arrays? [message #902047]

Wed, 15 August 2012 11:42

Dan Darnell
Messages: 145
Registered: November 2011
Location: Arkansas

Senior Member

Can I dynamically size or resize an array? In my case the array is multi-dimensional...

myarray boolean[][];

...and I want to set the array size based on a variable.

Is there a way to use resize() to dynamically set the array size? Or perhaps populate the array using appendElement() inside a loop?

I've tried several things but can't seem to figure out a) whether this is possible and b) how to make it work with a multi-dimensional array.

Thoughts?

--Dan

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Re: Dynamic arrays? [message #902076 is a reply to message #902047]

Wed, 15 August 2012 14:16

Brian Svihovec
Messages: 55
Registered: July 2009

Member

Dan,

It sounds like what you are asking for should be supported. Can you post a small snippet of code with your best guess at how this should be implemented? We can iterate on the EGL or the generated output from there. Also, what target language are you using for this snippet?

-Brian

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Re: Dynamic arrays? [message #902267 is a reply to message #902076]

Thu, 16 August 2012 12:26

Dan Darnell
Messages: 145
Registered: November 2011
Location: Arkansas

Senior Member

Hi Brian,

I'm targeting JavaScript.

The syntax that I would like to use would be simply:

foo int = 20;
bar int = 25;

myArray1 boolean[] = new boolean[foo];
myArray2 boolean[][] = new boolean[foo][bar];

If I'm not mistaken, this syntax is directly supported in Java. In generated JavaScript it might require setting up a looping structure to initialize the array.

With EGL as it exists today I tried several variations using resize() but without really understanding what resize() is intended to do. I also tried setting up my own loops and using appendElement() to dynamically expand and initialize the array dimensions.

This works:

b boolean[];
for(i int from 1 to 10)
  b.appendElement(false);
end
for(i int from 1 to 10)
  SysLib.writeStdout(b[i]);
end

But I never found a solution with appendElement() for a multi-dimensional array.

--Dan

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Re: Dynamic arrays? [message #902469 is a reply to message #902267]

Fri, 17 August 2012 14:31

Brian Svihovec
Messages: 55
Registered: July 2009

Member

Dan,

I believe the following code should do what you want:

foo int = 20;
bar int = 25;

myArray2 boolean[][] = new boolean[0][0];

myArray2.resize(foo); 
for(i int from 1 to myArray2.getSize())
	myArray2[i].resize(bar);
end

While this appears to run in Java for EDT, it does not appear to run in JavaScript. I have opened the following bug for this issue - https://bugs.eclipse.org/bugs/show_bug.cgi?id=387502

The following is an alternative solution that does appear to work in JavaScript:

foo int = 20;
bar int = 25;

myArray2 boolean[][] = new boolean[0][0];

for(i int from 1 to foo)
	innerArray boolean[] = new boolean[0];
	for(j int from 1 to bar)
		innerArray.appendElement(false);
	end
	myArray2.appendElement(innerArray);
end

-Brian

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Re: Dynamic arrays? [message #902509 is a reply to message #902469]

Fri, 17 August 2012 22:36

Dan Darnell
Messages: 145
Registered: November 2011
Location: Arkansas

Senior Member

Much appreciated! I figured there must be a way to do it using appendElement but I just couldn't figure out the secret sauce.

Any chance of the simple syntax that Java supports being implemented in EGL?

--Dan

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