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Boolean variables can either be True or False and are stored as 16-bit (2-byte) values. Boolean variables are displayed as either True or False. Like C, when other numeric data types are converted to Boolean values then a 0 becomes False and any other values become True.
It's a question many may ask when they discover that in C or C++ a Boolean variable or 'bool' for short, is simply an alias for a 4-byte unsigned integer (actually 1-byte oops). Shock horror! Any self-respecting novice in the field might ask “but we can fit eight booleans in just one byte!
Boolean variables are stored as 16-bit (2-byte) numbers, but they can only be True or False.
Why does a System. Boolean take 4 bytes? It just stores one state, either true or false, which could be stored in less space than 4 bytes.
In C#, certainly the bits aren't packed by default, so multiple bool fields will each take 1 byte. You can use BitVector32, BitArray, or simply bitwise arithmetic to reduce this overhead. As variables I seem to recall they take 4 bytes (essentially handled as int = Int32).
For example, the following sets i to 4:
struct Foo
{
public bool A, B, C, D;
}
static unsafe void Main()
{
int i = sizeof(Foo);
}
In C# they are stored as 1 byte in an array or a field but interestingly they are 4 bytes when they are local variables. I believe the 1-byteness of bool is defines somewhere in the .NET docs unlike Java. I suppose the reason for the 4 bytes for local variables are to avoid masking the bits when readng 32bits in a register. Still the sizeof operator shows 1 byte because this is the only relevant size and everything else is implementation detail.
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