• [first, last) is a valid range.
• Each iterator i in [first, last) points to a valid object.
Complexity The run-time complexity of the second version is linear: it calls the destructor exactly last – first times.
Example class Int {
public:
Int(int x) : val(x) {}
int get() { return val; }
private:
int val;
};
int main() {
Int A[] = { Int(1), Int(2), Int(3), Int(4) };
destroy(A, A + 4);
construct(A, Int(10));
construct(A + 1, Int(11));
construct(A + 2, Int(12));
construct(A + 3, Int(13));
}
Notes [1] In particular, destroy , along with other low-level memory allocation primitives, is used to implement container classes.
See also Allocators, construct, uninitialized_copy, uninitialized_fill, uninitialized_fill_n, raw_storage_iterator
Categories: allocators, algorithms
Component type: function
Prototype template <class InputIterator, class ForwardIterator>
ForwardIterator uninitialized_copy(InputIterator first, InputIterator last, ForwardIterator result);
Description In C++, the operator new allocates memory for an object and then creates an object at that location by calling a constructor. Occasionally, however, it is useful to separate those two operations. [1] If each iterator in the range [result, result + (last – first)) points to uninitialized memory, then uninitialized_copy creates a copy of [first, last) in that range. That is, for each iterator i in the input range, uninitialized_copy creates a copy of *i in the location pointed to by the corresponding iterator in the output range by calling construct(&*(result + (i – first)), *i).
Definition Defined in the standard header memory, and in the nonstandard backward-compatibility header algo.h.
Requirements on types • InputIterator is a model of Input Iterator.
• ForwardIterator is a model of Forward Iterator.
• ForwardIterator is mutable.
• ForwardIterator's value type has a constructor that takes a single argument whose type is InputIterator 's value type.
Preconditions • [first, last) is a valid range.
• [result, result + (last – first)) is a valid range.
• Each iterator in [result, result + (last – first)) points to a region of uninitialized memory that is large enough to store a value of ForwardIterator's value type.
Complexity Linear. Exactly last – first constructor calls.
Example class Int {
public:
Int(int x) : val(x) {}
int get() { return val; }
private:
int val;
};
int main() {
int A1[] = {1, 2, 3, 4, 5, 6, 7};
const int N = sizeof(A1) / sizeof(int);
Int* A2 = (Int*) malloc(N * sizeof(Int));
uninitialized_copy(A1, A1 + N, A2);
}
Notes [1] In particular, this sort of low-level memory management is used in the implementation of some container classes.
See also Allocators, construct, destroy, uninitialized_fill, uninitialized_fill_n, raw_storage_iterator
Categories: allocators, algorithms
Component type: function
Prototype template <class InputIterator, class Size, class ForwardIterator>
ForwardIterator uninitialized_copy_n(InputIterator first, Size count, ForwardIterator result);
