bitwise_operations_explained.md

Bitwise Operations Explained

Bitwise operators work directly on the bits of integer values. They are essential for flags, low-level hardware control, and optimization.

Operators

Operator	Meaning	Example
&	AND	a & b
`	`	OR
^	XOR	a ^ b
~	NOT (complement)	~a
<<	Left shift	a << n
>>	Right shift	a >> n

Common Patterns

• Setting a bit: flags |= (1 << bit_position)
• Clearing a bit: flags &= ~(1 << bit_position)
• Toggling a bit: flags ^= (1 << bit_position)
• Checking a bit: if (flags & (1 << bit_position))

Use uint8_t, uint32_t, etc. from <stdint.h> for predictable sizes.

Best Practices

• Use named constants for bit positions
• Comment your bit operations clearly
• Be careful with signed integers and right shifts (sign extension)
• Prefer bitwise for flags instead of multiple bool variables

Exercises

1. Write a function that counts the number of set bits in a number.
2. Implement simple permission flags (read/write/execute) using bits.
3. Create a function that checks if a number is a power of 2 using bitwise ops.
4. Combine with your structs: add a bitfield for status flags in a struct.

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Compile:

gcc -std=c23 -Wall -Wextra -Wpedantic bitwise_operations.c -o bitwise