Number 2

Bitwise Operator


Bitwise Structures

What is Bitwise Structure?

  • The smallest type is of 8 bits (char).
  • Sometimes we need only a single bit.
  • For instance, storing the status of the lights in 8 rooms:
    • We need to define an array of at least 8 chars.
      If the light of room 3 is turned on the value of
      the third char is 1, otherwise 0.
    • Total array of 64 bits.
  • It is better to define only 8 bits since a bit can also store the values 0 or 1.
  • But the problem is that there is no C type which is
    1 bit long (char is the longer with 1 byte).
  • Solution: define a char (8 bits) but refer to each bit separately.
  • Bitwise operators, introduced by the C language, provide one of its more powerful tools for using and manipulating memory. They give the language the real power of a “low-level language”.
  • Accessing bits directly is fast and efficient, especially if you are writing a real-time application.
  • A single bit cannot be accessed directly,
    since it has no address of its own.
  • The language introduces the bitwise operators, which help in manipulating a
    single bit of a byte.
  • bitwise operators may be used on integral types only (unsigned types are preferable).
Bitwise Operators
Shift right
Shift left
1’s compliment
bitwise XOR
bitwise AND
bitwise OR
All these operators can be suffixed with =
For instance a &= b; is the same as a = a & b;