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copied!<p>Most methods in the array class only work with one-dimensional arrays, so you have to perform the copy manually:</p> <pre><code>T[,] ResizeArray<T>(T[,] original, int rows, int cols) { var newArray = new T[rows,cols]; int minRows = Math.Min(rows, original.GetLength(0)); int minCols = Math.Min(cols, original.GetLength(1)); for(int i = 0; i < minRows; i++) for(int j = 0; j < minCols; j++) newArray[i, j] = original[i, j]; return newArray; } </code></pre> <p>To understand why it doesn't work with <code>Array.Copy</code>, you need to consider the layout of a multidimensional array in memory. The array items are not <em>really</em> stored as a bidimensional array, they're stored contiguously, row after row. So this array:</p> <pre><code>{ { 1, 2, 3 }, { 4, 5, 6 } } </code></pre> <p>Is actually arranged in memory like that: <code>{ 1, 2, 3, 4, 5, 6 }</code></p> <p>Now, assume you want to add one more row and one more column, so that the array looks like this:</p> <pre><code>{ { 1, 2, 3, 0 }, { 4, 5, 6, 0 }, { 0, 0, 0, 0 } } </code></pre> <p>The layout in memory would now be as follows: <code>{ 1, 2, 3, 0, 4, 5, 6, 0, 0, 0, 0, 0 }</code></p> <p>But <code>Array.Copy</code> treats all arrays as one-dimensional. MSDN says:</p> <blockquote> <p>When copying between multidimensional arrays, the array behaves like a long one-dimensional array, where the rows (or columns) are conceptually laid end to end</p> </blockquote> <p>So when you try to copy the original array to the new one, it just copies one memory location to the other, which gives, in one-dimensional representation:</p> <p><code>{ 1, 2, 3, 4, 5, 6, 0, 0, 0, 0, 0, 0 }</code>.</p> <p>If you convert that to a two-dimensional representation, you get the following:</p> <pre><code>{ { 1, 2, 3, 4 }, { 5, 6, 0, 0 }, { 0, 0, 0, 0 } } </code></pre> <p>This is why you're getting a screwed up array... Note that it would work property if you changed the number of rows, but not the number of columns.</p>

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