Question

I’ve been studying C# and ran accross some familiar ground from my old work in C++. I never understood the reason for bitwise operators in a real application. I’ve never used them and have never had in a reason to use them. I’ve been studying how they work; the example below shows the shift bitwise operator. What is the point of bitwise operators, their use and how they work?

Maybe I’m missing something in bitwise logic.

byte bitComp = 15;              // bitComp = 15 = 00001111b
byte bresult = (byte) ~bitComp; // bresult = 240 = 11110000b

Here’s an example for the ~complement bitwise operator:

byte bitComp = 15;              // bitComp = 15 = 00001111b
byte bresult = (byte) ~bitComp; // bresult = 240 = 11110000b

Answer 1

A typical use is manipulating bits that represent mutually exclusive ‘flags’.

Example from MSDN: Enumeration Types

[Flags]
enum Days2
{
    None = 0x0,
    Sunday = 0x1,
    Monday = 0x2,
    Tuesday = 0x4,
    Wednesday = 0x8,
    Thursday = 0x10,
    Friday = 0x20,
    Saturday = 0x40
}

class MyClass
{
    Days2 meetingDays = Days2.Tuesday | Days2.Thursday;

    Days2 notWednesday = ~(Days2.Wednesday);
}

See also Stack Overflow question Most common C# bitwise operations.