取模运算在c++11中用%表示。
根据ISO14882:2011(e)
The binary / operator yields the quotient, and the binary % operator yields the remainder from the division of the first expression by the second. If the second operand of / or % is zero the behavior is undefined. For integral operands the / operator yields the algebraic quotient with any fractional part discarded; if the quotient a/b is representable in the type of the result, (a/b)*b + a%b is equal to a.
(-7/3)→ -2
-2*3→-6
so (-7%3)→-1
(7/-3)→-2
-2*-3→6
so (7%-3)→1
与我想象的取模还是有差异的 - . -