C# 4 and .NET 4

258 ❘ ChaPTer 10 cOllectiOns
starting index for new item(s): 1
new item(s):
Three
action: Remove
starting index for old item(s): 0
old item(s):
One
biT arrays
If you need to deal with a number of bits, you can use the class BitArray and the struct BitVector32.
BitArray is located in the namespace System.Collections; BitVector32 is in the namespace System.
Collections.Specialized. The most important difference between these two types is that BitArray is
resizable, which is useful if you don’t know the number of bits needed in advance, and it can contain a large
number of bits. BitVector32 is stack-based and therefore faster. BitVector32 contains only 32 bits, which
are stored in an integer.
bitarray
The class BitArray is a reference type that contains an array of ints, where for every 32 bits a new integer
is used. Members of this class are explained in the following table:
biTarray members
Count Length
Item Get() Set()
SetAll()
Not()
And() Or() Xor()
desCriPTion
The get accessor of both Count and Length return the number of bits in the
array. With the Length property, you can also define a new size and resize the
collection.
You can use an indexer to read and write bits in the array. The indexer is of type bool.
Instead of using the indexer, you can also use the Get() and Set() methods to
access the bits in the array.
The method SetAll() sets the values of all bits according to the parameter passed
to the method.
The method Not() generates the inverse of all bits of the array.
With the methods And(), Or(), and Xor(), you can combine two BitArray objects.
The And() method does a binary AND, where the result bits are set only if the bits
from both input arrays are set. The Or() method does a binary OR, where the result
bits are set if one or both of the input arrays are set. The Xor() method is an exclusive
OR, where the result is set if only one of the input bits is set.
The helper method DisplayBits() iterates through a BitArray and displays 1 or 0 to the console, depending
on whether or not the bit is set:
static void DisplayBits(BitArray bits)
{
foreach (bool bit in bits)
{
Console.Write(bit 1: 0);
}
}
code snippet BitArraySample/Program.cs
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