A constant expressions can be evaluated during translation rather that runtime and accordingly may be used in any place that a constant may be.

Constant expressions can consist only of the following:

• literals,
• enumeration constants,
• simple constants (no constant arrays or structures),
• sizeof operators.

Constant expressions cannot contain any of the following operators, unless the operators are contained within the operand of a sizeof operator: assignment, comma, decrement, function call, increment.

Each constant expression can evaluate to a constant that is in the range of representable values for its type.

Constant expression can be used anywhere a constant is legal.

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