Convert list of float[] to list of double[]

Question

I want to convert a List<float[]> to List<double[]>

List<float[]> f=new List<float[]>();
List<double[]> d=new List<double[]>();

// ...add float arrays to f...

d.AddRange((doulbe[])f); // Cannot convert type float[] to double[]

is there a way to cast this? so that it won't require a for loop, because I have many lists to be converted.

The AddRange is implemented as a for loop. You need to do the same (using a for loop, a linq query or anything that enumerate your collection). You can't do it in place — saad, Mar 09 '21 at 10:19
Remember that a `float` and a `double` are different sizes. You can't just take the bits from a `float` and re-interpret them as a `double`. This is what you're asking the cast to do however. — canton7, Mar 09 '21 at 10:20
[C# Cast Entire Array?](https://stackoverflow.com/questions/2068120/c-sharp-cast-entire-array) — Pavel Anikhouski, Mar 09 '21 at 10:21
@DmitryBychenko Saldly this does not work, you get a InvalidCastException, but it was my first thought as well — Irwene, Mar 09 '21 at 10:21
Yeah, remember that you can't use generics to invoke user-defined conversion operators — canton7, Mar 09 '21 at 10:22
@canton7 I am converting from a lower precision to a higher precision, so it does not lose anything from the numbers. — Mario, Mar 09 '21 at 10:45
Right, but my point was that an array cast (strictly, a reference conversion) is a different way of looking at the same underlying bits in memory. You can't take the underlying bits of a float and look at them as if they were a double, so an array cast is not going to work. — canton7, Mar 09 '21 at 10:49

Tim Schmelter · Accepted Answer · 2021-03-09T10:49:48.070

3

You can use:

d.AddRange(f.Select(flArray => Array.ConvertAll(flArray, f => (double)f)));

or:

f.ForEach(flArray => d.Add(Array.ConvertAll(flArray, f => (double)f)));

edited Mar 09 '21 at 10:49

answered Mar 09 '21 at 10:23

Tim Schmelter

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Convert list of float[] to list of double[]

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