std::hive<T,Allocator>::unique
template< class BinaryPredicate = std::equal_to<T> >
size_type unique( BinaryPredicate binary_pred = BinaryPredicate() );
|
(since C++26) | |
Removes all consecutive duplicate elements from the container. Only the first element in each group of equal elements is left.
More formally, for a nonempty hive, erases all elements referred to by the iterator i in the [begin() + 1, end()) for which p(*i, *(i - 1)) is true.
Invalidates references, pointers, and iterators referring to the erased elements.
If the last element in *this is erased, also invalidates the past-the-end iterator.
The behavior is undefined if the corresponding comparator does not establish an equivalence relation.
Parameters
| p | - | binary predicate which returns true if the elements should be treated as equal. The signature of the predicate function should be equivalent to the following:
While the signature does not need to have |
| Type requirements | ||
-BinaryPredicate must meet the requirements of BinaryPredicate.
|
Return value
The number of elements removed.
Complexity
If empty() is true, no comparison is performed.
Otherwise, given N as std::distance(begin(), end()):
exactly N-1 applications of the predicate p.
Example
#include <iostream>
#include <hive>
std::ostream& operator<< (std::ostream& os, const std::hive<int>& container)
{
for (int val : container)
os << val << ' ';
return os << '\n';
}
int main()
{
std::hive<int> c{1, 2, 2, 3, 3, 2, 1, 1, 2};
std::cout << "Before unique(): " << c;
const auto count1 = c.unique();
std::cout << "After unique(): " << c
<< count1 << " elements were removed\n";
c = {1, 2, 12, 23, 3, 2, 51, 1, 2, 2};
std::cout << "\nBefore unique(pred): " << c;
const auto count2 = c.unique([mod = 10](int x, int y)
{
return (x % mod) == (y % mod);
});
std::cout << "After unique(pred): " << c
<< count2 << " elements were removed\n";
}
Output:
Before unique(): 1 2 2 3 3 2 1 1 2
After unique(): 1 2 3 2 1 2
3 elements were removed
Before unique(pred): 1 2 12 23 3 2 51 1 2 2
After unique(pred): 1 2 23 2 51 2
4 elements were removed
See also
| removes consecutive duplicate elements in a range (function template & algorithm function object) | |
(C++20) |