BitVector32 - first bit true

Question

I am a bit puzzled with BitVector32 behaviour. See the test:

[TestClass]
public class ParallelPortDevices {
    [TestMethod]
    public void BitVector32Test() {
        var lVector = new BitVector32(0);

        Assert.IsTrue(lVector[0]);
        Assert.IsFalse(lVector[1]);
    }
}

This passes. I.e. the first bit is set to 1 (according to the test). However if you run the ToString method you will get "BitVector32{00000000000000000000000000000000}"

Anything I am missing?

Thanks in advance!

Answer 1

BitVector32 does not use the indexer syntax for index, it uses it as a bitmask. For example, if you were to do this:

lVector[7] = true;

ToString would give 0...000111.

The decompiled code for the getter looks like this:

return ((long) this.data & (long) bit) == (long) (uint) bit;

So what ends up happening is this:

(0 & 0) == 0

Which of course, is true.