How can I convert BitArray to single int?

Question

How can I convert BitArray to a single int?

Answer 1

This version:

• works for up to 64 bits
• doesn't rely on knowledge of BitArray implementation details
• doesn't needlessly allocate memory
• doesn't throw any exceptions (feel free to add a check if you expect more bits)
• should be more than reasonably performant

Implementation:

public static ulong BitArrayToU64(BitArray ba)
{
    var len = Math.Min(64, ba.Count);
    ulong n = 0;
    for (int i = 0; i < len; i++) {
        if (ba.Get(i))
            n |= 1UL << i;
    }
    return n;
}