Convert int & # 8594; unsigned long long defined by standard

Question

I cannot find an exact specification of how the value is intconverted to unsigned long longin the standard. Various similar transformations will be defined, such as int → unsigned, unsigned → int (UB if negative), unsigned long long → int, etc.

For example, GCC is -1converted to 0xffffffffffffffff, not to 0x00000000ffffffff. Can I rely on this behavior?

Answer 1

, , max unsigned long long + 1 -1, max unsigned long long. ++ 4.7 , :

, ( 2 , ). [. ( ). -end note]

, C99, C99 , 6.3.1.3 Signed :

, , , . ⁴⁹⁾

49 :

, .

Answer 2

, :

++ 11 § 4.7 [conv.integral]/2 :

, ( 2 , ).

, -1 ( 2 ^{sizeof(unsigned long long)}), unsigned long long.

Answer 3

. , int v unsigned long u , u= K * 2 ⁿ + v, K - 0, 1, n - unsigned long. , v , 2 ⁿ.

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2 ++ , . n 2 ⁿ. ( std::numeric_limits ).

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, , , , -, undefined, unsigned . , , Visual ++ . , , , ( ) .