Bit Manipulation Techniques

Bit tricks are useful for flags, fast arithmetic, and low‑level protocols.

Task	Expression
Set bit n	`x
Clear bit n	x &= ~(1U << n);
Toggle bit n	x ^= (1U << n);
Test bit n	(x & (1U << n)) != 0
Count set bits	Kernighan’s algorithm: while(x){x &= x-1; ++count;}
Is power of two?	x && !(x & (x-1))

These operations are O(1) and often replace loops.

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📚 Example: Counting Bits in an Unsigned Integer

unsigned int count_bits(unsigned int x) {
    unsigned int c = 0;
    while (x) {
        x &= x - 1; // clear least‑significant 1‑bit
        ++c;
    }
    return c;
}