Symbols:C

Hexadecimal

 * $\mathrm C$ or $\mathrm c$

The hexadecimal digit $12$.

The Set of Complex Numbers

 * $\C$

The set of complex numbers.

The Set of Non-Zero Complex Numbers

 * $\C^*$

The set of non-zero complex numbers:
 * $\C^* = \C - \left\{{0}\right\}$

Relative Complement

 * $\complement_S \left({T}\right)$ or $\mathcal C_S \left({T}\right)$

Set Complement

 * $\complement \left ({S}\right)$ or $\mathcal C \left ({S}\right)$