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How to Convert a byte array into an int array? I have a byte array holding 144 items and the ways I have tried are quite inefficient due to my inexperience. I am sorry if this has been answered before, but I couldn't find a good answer anywhere.

user1166981
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5 Answers5

36

Simple:

//Where yourBytes is an initialized byte array.
int[] bytesAsInts = yourBytes.Select(x => (int)x).ToArray();

Make sure you include System.Linq with a using declaration:

using System.Linq;

And if LINQ isn't your thing, you can use this instead:

int[] bytesAsInts = Array.ConvertAll(yourBytes, c => (int)c);
vcsjones
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  • I got an error: 'byte[]' does not contain a definition for 'Select' and no extension method 'Select' accepting a first argument of type 'byte[]' could be found (are you missing a using directive or an assembly reference?) – user1166981 Jun 20 '12 at 03:04
  • @user1166981: Make sure to reference `System.Linq` in your project. (Which version of the .NET framework are you targeting, by the way?) – Ry- Jun 20 '12 at 03:05
  • This approach is very slow: Linq is not optimized for `byte` block copies. It's _much_ faster to do `int[] bytesAsInts = new int[ yourBytes.Length / 2 ]; Buffer.BlockCopy( yourBytes, 0, bytesAsInts, 0, yourBytes.Length );`. – Dai Aug 03 '21 at 08:40
12

I known this is an old post, but if you were looking in the first place to get an array of integers packed in a byte array (and it could be considering your array byte of 144 elements), this is a way to do it:

var size = bytes.Count() / sizeof (int);
var ints = new int[size];
for (var index = 0; index < size; index++)
{
    ints[index] = BitConverter.ToInt32(bytes, index * sizeof (int));
}

Note: take care of the endianness if needed. (And in most case it will)

Kevin Struillou
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    Nice, was looking for this. People seem to forget that (int)byteVar is not the same as converting a bytearray into an int (for example 4 bytes for one int) – Revils Jul 26 '17 at 06:47
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    There is a better solution: https://stackoverflow.com/a/5896716/238419 That question is about `int[]` to `byte[]` but this solution should work regardless – BlueRaja - Danny Pflughoeft Aug 28 '17 at 00:40
9

Now It's Simple like follows,

int[] result = Array.ConvertAll(bytesArray, Convert.ToInt32);
Dimuth Ruwantha
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9

Use Buffer.BlockCopy instead of Array.ConvertAll.

ref Converting an int[] to byte[] in C#

byte[] bytes = new byte[] { 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8 };
int[]  ints= Array.ConvertAll(bytes, Convert.ToInt32);

will return ints[]={0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8},

not return ints[]={0x04030201,0x08070605}

should use Buffer.BlockCopy(bytes, 0, ints, 0, bytes.Length);

wade.ec
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0

What you really need is:

Span<int> integerArray = MemoryMarshal.Cast<byte, int>(byteArray.AsSpan());

source -> https://stackoverflow.com/a/56029829/2791333

user2791333
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  • This is of course optimal from a performance point of view, but I don't think that was the questioner's intention. You are reinterpreting the byte array as an integer span. I guess the questioner wanted to have an array/span where each byte is seen as an individual integer. – Robin Lindner Aug 22 '23 at 05:03