BitArray to integer issue

问题

public static int getIntegerFromBitArray(BitArray bitArray)
{
  var result = new int[1];
  bitArray.CopyTo(result, 0);
  return result[0];
}

// Input  A) 01110
// Output A) 14
// Input  B) 0011
// Output B) 12 <=== ????? WHY!!! :)

Can some one please explain me why my second return value is 12 instead of 3?? Please ... Thank you.

回答1:

Basically it's considering the bits in the opposite order to the way you were expecting - you haven't shown how you're mapping your input binary to a BitArray, but the result is treating it as 1100 rather than 0011.

The documentation isn't clear, admittedly, but it does work the way I'd expect it to: bitArray[0] represents the least significant value, just as it usually is when discussing binary (so bit 0 is 0/1, bit 1 is 0/2, bit 2 is 0/4, bit 3 is 0/8 etc). For example:

using System;
using System.Collections;

class Program
{
    static void Main(string[] args)
    {
        BitArray bits = new BitArray(8);
        bits[0] = false;
        bits[1] = true;

        int[] array = new int[1];
        bits.CopyTo(array, 0);
        Console.WriteLine(array[0]); // Prints 2
    }
}

回答2:

You need rotate bit's to right direction to get right results. 1100 is 12

来源：https://stackoverflow.com/questions/9697623/bitarray-to-integer-issue