26 Numerics library [numerics]

26.5 Bit manipulation [bit]

26.5.3 Function template bit_­cast [bit.cast]

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template<class To, class From> constexpr To bit_cast(const From& from) noexcept;
1
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Constraints:
  • (1.1)
    sizeof(To) == sizeof(From) is true;
  • (1.2)
    is_­trivially_­copyable_­v<To> is true; and
  • (1.3)
    is_­trivially_­copyable_­v<From> is true.
2
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Returns: An object of type To.
Implicitly creates objects nested within the result ([intro.object]).
Each bit of the value representation of the result is equal to the corresponding bit in the object representation of from.
Padding bits of the result are unspecified.
For the result and each object created within it, if there is no value of the object's type corresponding to the value representation produced, the behavior is undefined.
If there are multiple such values, which value is produced is unspecified.
3
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Remarks: This function is constexpr if and only if To, From, and the types of all subobjects of To and From are types T such that:
  • (3.1)
    is_­union_­v<T> is false;
  • (3.2)
    is_­pointer_­v<T> is false;
  • (3.3)
    is_­member_­pointer_­v<T> is false;
  • (3.4)
    is_­volatile_­v<T> is false; and
  • (3.5)
    T has no non-static data members of reference type.