Operators

C supports the usual arithmetic (+ - * / % ++ --), comparison (== != > < >= <=), logical (&& || !), and — used more often than in most languages — bitwise (& | ^ ~ << >>) operators.

int a = 7, b = 2;
printf("%d\n", a % b);   // 1 — remainder

int flags = 0b0110;
int masked = flags & 0b0010; // bitwise AND
printf("%d\n", masked);       // 2

Common mistakes

• Confusing &&/|| (logical) with &/| (bitwise) — using a single & where && was meant compiles fine but silently does something completely different.
• Writing if (x = 5) instead of if (x == 5) — this is legal C (it assigns 5 to x, and the condition is then always true), and one of the most notorious C beginner bugs. Most compilers warn about this if you enable warnings (-Wall).