Bitwise Operators

In C, byte is the lowest level where we can perform an operation. Applying these Bitwise operators on bytes helps us perform bit level operation. When you combine these operators with any two bytes, it results in another byte (8-bits).

Suppose we have two numbers 3 and 6. With basic arithmetic knowledge, we say 3 + 6 =9. Here 3 and 6 are the Operands, "+" is the Operator and 9 is the result. Keeping this in mind, we will apply the same logic on a set of binary digits.  Consider two variables “a” and “b”.

a = 01101111 = 0x6f
b = 10011001 = 0x99

Bitwise Operators available in C are: AND (&), OR (|), XOR (^) and NOT (~). There are also bit shift operators viz. Bit left shift (<<) and Bit right shift (>>) operators. We will apply these operators on bits and see the result in a truth table.

&       :       Bitwise "AND" Operator.

Truth Table

1 & 1 = 1
1 & 0 = 0
0 & 1 = 0
0 & 0 = 0

The result is 1 if both the operands are 1, else 0.
a & b = 01101111 & 10011001 = 00001001 = 0x09

|       :       Bitwise "OR" Operator

1 | 1 = 1
1 | 0 = 1
0 | 1 = 1
0 | 0 = 0
Here, the result is 1 if any of the operands are 1, else 0.
a | b = 01101111 | 10011001 = 11111111 = 0xff

^       :       Bitwise "XOR" Operator

1 ^ 1 = 0
1 ^ 0 = 1
0 ^ 1 = 1
0 ^ 0 = 0

For XOR Operator between two operands, the result is 1 if and only if one of the operand is 1, not both.

a ^ b = 01101111 ^ 10011001 = 11110110 = 0xf6

~       :       Bitwise "NOT" Operator (A.K.A Bitwise Ones Complement)

~1 = 0
~0 = 1

This operator does nothing more than flipping a bit from 1 to 0 and 0 to 1.

~a = ~(01101111) = 10010000 = 0x90
~b = ~(10011001) = 01100110 = 0x66

Next we will look at Bit shift / Binary shift Operators. Binary shift operators are used to shift bits to left or right as specified in the right operand.

Tutorial index:

1. Introduction: 
2. Electronics:
3. Breadboard-Programmer Setup:
4. Programming:
5. Blinking LED:
6. Bitwise Operators:
7. Assignment Operators:
8. Bitwise Shift Operators:

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