What is the behavior of integer division?

Will result always be the floor of the division? What is the defined behavior?

Not quite. It rounds toward 0, rather than flooring.

6.5.5 Multiplicative operators

6 When integers are divided, the result of the / operator is the algebraic quotient with any
fractional part discarded.88) If the quotient a/b is representable, the expression
(a/b)*b + a%b shall equal a.

and the corresponding footnote:

  1. This is often called ‘‘truncation toward zero’’.

Of course two points to note are:

3 The usual arithmetic conversions are performed on the operands.


5 The result of the / operator is the
quotient from the division of the
first operand by the second; the
result of the % operator is the
remainder. In both operations, if the
value of the second operand is zero,
the behavior is undefined.

[Note: Emphasis mine]

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