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Do I always have `(a / b * b) + a % b == a` when b is not zero?

原文 2012-09-02 01:04:59 5 1 c++/ c

For int a, b , I know that when there is exactly one of a and b is negative, the result of a / b and a % b is machine dependent. But do I always have (a / b * b) + a % b == a when b is not zero?

1 answers

C++11 §5.6[expr.mul]/4 specifies:

If the quotient a/b is representable in the type of the result, (a/b)*b + a%b is equal to a .

C11 §6.5.5/6 specifies the same with slightly different phrasing:

If the quotient a/b is representable, the expression (a/b)*b + a%b shall equal a ; otherwise, the behavior of both a/b and a%b is undefined.

Given that b is always non-zero, why `b ? --b : ++b` works, but `--b` does not?

When I do int a = std::move(b) (b is int also), is it same as just a = b?

Why does a%b produce SIGFPE when b is zero?

I have a variable b in parent class and when i try to access variable b from sum3 class it shows ambiguous b error

For { A=a; B=b; }, will “A=a” be strictly executed before “B=b”?

undefined reference to B::B & B::~B

How do I implement A into B and B into A (without creating a loop)?

I want to know why only b is returned when I do like return(a,b)

Is ++(a = b); faster than a = b + 1;?

Equivalence of “a @= b” and “a = a @ b”

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Related Question Given that b is always non-zero, why `b ? --b : ++b` works, but `--b` does not? When I do int a = std::move(b) (b is int also), is it same as just a = b? Why does a%b produce SIGFPE when b is zero? I have a variable b in parent class and when i try to access variable b from sum3 class it shows ambiguous b error For { A=a; B=b; }, will “A=a” be strictly executed before “B=b”? undefined reference to B::B & B::~B How do I implement A into B and B into A (without creating a loop)? I want to know why only b is returned when I do like return(a,b) Is ++(a = b); faster than a = b + 1;? Equivalence of “a @= b” and “a = a @ b”

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Do I always have `(a / b * b) + a % b == a` when b is not zero?

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1 answers

solution1 18 ACCPTED 2012-09-02 01:07:57

solution1
18 ACCPTED 2012-09-02 01:07:57