Correct way to convert 8 bools into 1 byte

Question

Simple question: considering that a bool (true, false) is the same as a bit (1, 0), what is the correct way to convert eight bools into a byte in C#?

Examples:

true, true, true, true, true, true, true, true == 11111111 == 255

true, false, false, false, false, false, false, false == 10000000 == 128

false, false, false, false, false, false, false, false == 00000000 == 0

The above is the first part. I want to create an extension method, like that:

    public static byte[] ToByteArray(this bool[] bitArray)
    {
          // stuff here
          return byteArray;    
    }

The result must be a byteArray that contains eight times less elements than the bool array.

You're asking how to covert 8 bools into a byte, but your example method is returning a byte array. — itsme86, Sep 10 '13 at 15:07
Yep, like I said, the byteArray is the second part, first I need to convert 8 bools to 1 byte — Guilherme, Sep 10 '13 at 15:11

Tigran · Accepted Answer · 2013-09-10T15:10:51.630

13

You probabbly searching for BitArray Constructor (Boolean[])

For rapresenting bits you have special structure BitArray in C#. So your code would look like this:

var booleans = new bool[]{true, false, false, false};
var bitArray = new BitArray(booleans);

edited Sep 10 '13 at 15:10

answered Sep 10 '13 at 15:06

Tigran

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Is a good solution, but beware of the bug when specified a length and using `SetAll(true)` because that would result in -1(which is all bits for an int), instead of the given length. – Silvermind Sep 10 '13 at 15:10
So, how can I return a byte[] from that? – Guilherme Sep 10 '13 at 15:12
2

@Guilherme: `CopyTo()`. – SLaks Sep 10 '13 at 15:15
1

@Guilherme http://stackoverflow.com/questions/560123/convert-from-bitarray-to-byte – Adam Houldsworth Sep 10 '13 at 15:17

score 1 · Answer 2 · edited Feb 14 '20 at 12:20

1

Robust solution (just in case).

Split them into groups of 8 somehow (depending on the order and how you want to adjust them - to LSB or RSB), then form an array by calling this method in the cycle:

byte GetByte(bool[] bits)
{
    byte result = 0;
    for(int i = 0; i < bits.Length; i++)
        if(byte[i])
            result |= 1 << i;
    return result;
}

edited Feb 14 '20 at 12:20

Thomas Weller

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answered Sep 10 '13 at 15:26

Sinatr

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@LS_dev, yeah thanks. I mentioned, what `bytes` for method should be *prepared* first ^^, but you can add bound check and throw `ArgumentOutOfRangeException` or whatever if you want to, it was just an example of how easy to convert anything into bits. – Sinatr Sep 11 '13 at 06:51

Correct way to convert 8 bools into 1 byte

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