C# convert ReadOnlyCollection to byte[] array

Question

Given a read only collection of ints, how do I convert it to a byte array?

ReadOnlyCollection<int> collection = new List<int> { 118,48,46,56,46,50 }.AsReadOnly(); //v0.8.2

What will an elegant way to convert 'collection' to byte[] ?

Yes, 0 to 225. I plan to use the bitConverter to convert it to string. As for the endiannass, can be both. — Rotem Varon, Mar 22 '18 at 06:00
Possible duplicate of [C# int byte conversion](https://stackoverflow.com/questions/3641274/c-sharp-int-byte-conversion) — mjwills, Mar 22 '18 at 06:01

Alex Wiese · Accepted Answer · 2018-03-22T05:49:25.690

4

You can use LINQ's Select method to cast each element from int to byte. This will give you an IEnumerable<byte>. You can then use the ToArray() extension method to convert this to a byte[].

collection.Select(i => (byte)i).ToArray();

If you don't want to use LINQ then you can instantiate the array and use a for loop to iterate over the collection instead, assigning each value in the array.

var byteArray = new byte[collection.Count];

for (var i = 0; i < collection.Count; i++)
{
    byteArray[i] = (byte)collection[i];
}

edited Mar 22 '18 at 05:49

answered Mar 22 '18 at 05:43

Alex Wiese

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`int` can not be simple cast to `byte` – Backs Mar 22 '18 at 05:48
I think it can if the value is 0 to 255 @Backs ? – mjwills Mar 22 '18 at 06:04
The cast is always possible, a value outside the byte range will be truncated. – thehennyy Mar 22 '18 at 06:55
Is the order guaranteed with LINQ? – Rotem Varon Mar 22 '18 at 13:46
@RotemVaron the order will be the same as the original collection, unless you specify `OrderBy` – Alex Wiese Mar 22 '18 at 22:39

C# convert ReadOnlyCollection to byte[] array

1 Answers1