Matrix display row wise

I know the default ArrayItems-Tag can handle matrices, but I find the result insufficient.

Given this example

#include <cstdlib>
#include <cstdio>

struct matrix {
  int height;
  int width;
  double* values;
};

int main() {
  double* values = (double*)malloc(5 * 2 * sizeof(double));
  for (int i = 0; i < 10; ++i) values[i] = i * 2;
  matrix m = { 5, 2, values };

  return 0;
}

With this natvis

<?xml version="1.0" encoding="utf-8"?> 
<AutoVisualizer xmlns="http://schemas.microsoft.com/vstudio/debugger/natvis/2010">
  <Type Name="matrix">
    <DisplayString>{{Shape [{height} x {width}]}}</DisplayString>
    <Expand>
        <CustomListItems>
          <Variable Name="i" InitialValue="0" />
          <Loop>
            <Break Condition="i == height" />
            <Item>(values + (i * width)), 2</Item>
            <Exec>i++</Exec>
          </Loop>
        </CustomListItems>
      </Expand>
  </Type>
</AutoVisualizer>

Results in this output, which is nearly perfect.

• I wish the addresses wouldn't be shown
• I wish I could give a custom format specifier for the elements ( something like %.2f )

But I cheated in my natvis. I wrote <Item>(values + (i * width)), 2</Item> The 2 being the width of the row. But if I write width instead of the 2 it puts out 2 instead of the rows. It apparently prints the value of width, which is not helpful.

Anyone know how I can make these rows variable sized?

Try [width] nag:

<Item>(values + (i * width)), [width] nag</Item>

• The [size] - expand fixed-size array,
• na - "no address" - suppress address,
• g - for better view of floating point data.