std::stable_partition
Defined in header
<algorithm>
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template< class BidirIt, class UnaryPredicate >
BidirIt stable_partition( BidirIt first, BidirIt last, UnaryPredicate p ); |
(1) | |
template< class ExecutionPolicy, class BidirIt, class UnaryPredicate >
BidirIt stable_partition( ExecutionPolicy&& policy, BidirIt first, BidirIt last, UnaryPredicate p ); |
(2) | (since C++17) |
[first, last)
in such a way that all elements for which the predicate p
returns true precede the elements for which predicate p
returns false. Relative order of the elements is preserved. policy
. This overload does not participate in overload resolution unless std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is true
Contents |
[edit] Parameters
first, last | - | the range of elements to reorder |
policy | - | the execution policy to use. See execution policy for details. |
p | - | unary predicate which returns true if the element should be ordered before other elements. The signature of the predicate function should be equivalent to the following: bool pred(const Type &a); The signature does not need to have const &, but the function must not modify the objects passed to it. |
Type requirements | ||
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BidirIt must meet the requirements of ValueSwappable and BidirectionalIterator .
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-The type of dereferenced BidirIt must meet the requirements of MoveAssignable and MoveConstructible .
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UnaryPredicate must meet the requirements of Predicate .
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[edit] Return value
Iterator to the first element of the second group
[edit] Complexity
Exactly last-first
applications of the predicate and at most (last-first)*log(last-first)
swaps if there is insufficient memory or linear number of swaps if sufficient memory is available.
[edit] Exceptions
The overload with a template parameter named ExecutionPolicy
reports errors as follows:
- If execution of a function invoked as part of the algorithm throws an exception,
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- if
policy
is std::parallel_vector_execution_policy, std::terminate is called - if
policy
is std::sequential_execution_policy or std::parallel_execution_policy, the algorithm exits with an std::exception_list containing all uncaught exceptions. If there was only one uncaught exception, the algorithm may rethrow it without wrapping in std::exception_list. It is unspecified how much work the algorithm will perform before returning after the first exception was encountered. - if
policy
is some other type, the behavior is implementation-defined
- if
- If the algorithm fails to allocate memory (either for itself or to construct an std::exception_list when handling a user exception), std::bad_alloc is thrown.
[edit] Notes
This function attempts to allocate a temporary buffer, typically by calling std::get_temporary_buffer. If the allocation fails, the less efficient algorithm is chosen.
[edit] Example
#include <iostream> #include <algorithm> #include <vector> int main() { std::vector<int> v{0, 0, 3, 0, 2, 4, 5, 0, 7}; std::stable_partition(v.begin(), v.end(), [](int n){return n>0;}); for (int n : v) { std::cout << n << ' '; } std::cout << '\n'; }
Output:
3 2 4 5 7 0 0 0 0
[edit] See also
divides a range of elements into two groups (function template) |
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(parallelism TS)
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parallelized version of std::stable_partition (function template) |