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digitalmars.D.learn - Initializing multidimentional Array with a struct

reply "Chris Pons" <cmpons gmail.com> writes:
I'm trying to figure out how to initialize a multi-dimentional 
array with a struct. I thought it would be straight forward, but 
i'm running into problems. I'm using nested for loops, and just 
setting the current index to a blank version of my struct but 
that gives me this error: "Error: no [] operator overload for 
type Node". I didn't know I needed to overload that operator, 
usually didn't need to in C++ as far as I remember.

struct Node
{
     bool walkable;		
     vect2 position;		
     int	xIndex, yIndex;
     Node*[4] connections;
}

void InitializePathGraph()
{
     for( int x = 0; x < mapWidth; x++ )
     {
	for( int y = 0; y < mapHeight; y++ )
	{
	    Node node;
	    PathGraph[x][y] = node;// ERROR
	}
     }
}
Mar 31 2012
next sibling parent "Chris Pons" <cmpons gmail.com> writes:
I also tried this, which gives an out of range error:

	void InitializePathGraph()
	{
		PathGraph.length = mapWidth;
		foreach( elem; PathGraph )
		{
			elem.length = mapHeight;
		}
		
		Node node;

		for( int x = 0; x < mapWidth - 1; x++ )
		{
			for( int y = 0; y < mapHeight - 1; y++ )
			{
				
				PathGraph[x][y] = node;
			}
		}
	}

This is really confusing me.
Mar 31 2012
prev sibling parent reply =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 03/31/2012 02:34 PM, Chris Pons wrote:

 I'm trying to figure out how to initialize a multi-dimentional array
 with a struct. I thought it would be straight forward, but i'm running
 into problems. I'm using nested for loops, and just setting the current
 index to a blank version of my struct but that gives me this error:
 "Error: no [] operator overload for type Node". I didn't know I needed
 to overload that operator, usually didn't need to in C++ as far as I
 remember.

 struct Node
 {
 bool walkable;
 vect2 position;
 int xIndex, yIndex;
 Node*[4] connections;
 }

 void InitializePathGraph()
 {
 for( int x = 0; x < mapWidth; x++ )
 {
 for( int y = 0; y < mapHeight; y++ )
 {
 Node node;
 PathGraph[x][y] = node;// ERROR
 }
 }
 }


Do you want to initialize with the default value of Node? Then it is as 
easy as the following:

import std.stdio;

struct Node
{}

void main()
{
     Node[2][3] a;       // fixed-length of fixed-length
     Node[][] b = new Node[][](2, 3);  // slice of slice

     writeln(a);
     writeln(b);
}

The output:

[[Node(), Node()], [Node(), Node()], [Node(), Node()]]
[[Node(), Node(), Node()], [Node(), Node(), Node()]]

Please note the different meanings of 2 and 3 for the fixed-length array 
and the new expression: lines and rows are swapped!

Ali
Mar 31 2012
parent "Chris Pons" <cmpons gmail.com> writes:
Yes sorry, I was looking to initialize to the default value of 
node. Thank you for the help!

On Saturday, 31 March 2012 at 21:59:50 UTC, Ali Çehreli wrote:

 On 03/31/2012 02:34 PM, Chris Pons wrote:

 I'm trying to figure out how to initialize a


 multi-dimentional array

 with a struct. I thought it would be straight forward, but


 i'm running

 into problems. I'm using nested for loops, and just setting


 the current

 index to a blank version of my struct but that gives me this


 error:

 "Error: no [] operator overload for type Node". I didn't know


 I needed

 to overload that operator, usually didn't need to in C++ as


 far as I

 remember.

 struct Node
 {
 bool walkable;
 vect2 position;
 int xIndex, yIndex;
 Node*[4] connections;
 }

 void InitializePathGraph()
 {
 for( int x = 0; x < mapWidth; x++ )
 {
 for( int y = 0; y < mapHeight; y++ )
 {
 Node node;
 PathGraph[x][y] = node;// ERROR
 }
 }
 }


 Do you want to initialize with the default value of Node? Then 
 it is as easy as the following:

 import std.stdio;

 struct Node
 {}

 void main()
 {
     Node[2][3] a;       // fixed-length of fixed-length
     Node[][] b = new Node[][](2, 3);  // slice of slice

     writeln(a);
     writeln(b);
 }

 The output:

 [[Node(), Node()], [Node(), Node()], [Node(), Node()]]
 [[Node(), Node(), Node()], [Node(), Node(), Node()]]

 Please note the different meanings of 2 and 3 for the 
 fixed-length array and the new expression: lines and rows are 
 swapped!

 Ali
Mar 31 2012