What is the behavior of integer division?

ghz 1years ago ⋅ 3079 views

Question

For example,

int result;

result = 125/100;

or

result = 43/100;

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

Answer

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.

and:

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]

#c