Bitwise Operators & Bit Flags

The six bitwise operators

& AND, | OR, ^ XOR, ~ NOT (flips every bit), << left shift (multiply by 2 per shift), >> right shift (divide by 2 per shift).

Set, clear, toggle, check a bit

These four patterns cover almost every bit-flag task.

unsigned int flags = 0;

flags |= (1 << 2);   // set bit 2
flags &= ~(1 << 2);  // clear bit 2
flags ^= (1 << 2);   // toggle bit 2

if (flags & (1 << 2)) {
    printf("bit 2 is set\n");
}

Why bit flags?

Packing multiple boolean options into one integer (each bit = one on/off flag) saves memory and is common in embedded systems, permission systems, and hardware registers.

Quick check: Which operator flips every bit of a value?

• ~ (NOT)
• ^ (XOR)
• & (AND)