Getting an unsafe fixed pointer to the start of a rectangular array

Question

Consider a 2D, rectangular array. Say:

int[,] values = new int[len1, len2];

How can you iterate through all of its values in unsafe code?

Drew Noakes · Accepted Answer · 2012-10-31 01:07:54Z

2

The following works in an unsafe context.

fixed (int* baseOffset = values)
{
    var offset = baseOffset;
    var count = len1 * len2;
    for (int i = 0; i < count; i++)
    {
        int value = *offset;
        // Do whatever you need to do here
        offset++;
    }
}

Note that to get a pointer to the first item in an array, the types must match. So if you have a byte* which you want to treat as ushort*, you cannot cast the pointer within the fixed statement's parentheses, although you can do this within the block.

edited Oct 31, 2012 at 1:07

answered Oct 31, 2012 at 0:55

Drew Noakes

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