std::stable_partition
Defined in header <algorithm> |
||
---|---|---|
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>>
(until C++20)
std::is_execution_policy_v<std::remove_cvref_t<ExecutionPolicy>>
(since C++20) is true.
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 expression |
Type requirements | ||
-BidirIt must meet the requirements of ValueSwappable and LegacyBidirectionalIterator. |
||
-The type of dereferenced BidirIt must meet the requirements of MoveAssignable and MoveConstructible. |
||
-UnaryPredicate must meet the requirements of Predicate. |
Return value
Iterator to the first element of the second group.
Complexity
Given N = std::distance(first, last)
,
N
applications of the predicate and
O(N)
swaps if there is enough extra memory. If memory is insufficient, at most
N log N
swaps.
O(N log N)
swaps and
O(N)
applications of the predicate
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 and
ExecutionPolicy
is one of the standard policies,std::terminate
is called. For any otherExecutionPolicy
, the behavior is implementation-defined. - If the algorithm fails to allocate memory,
std::bad_alloc
is thrown.
Notes
This function attempts to allocate a temporary buffer. If the allocation fails, the less efficient algorithm is chosen.
Implementations in libc++ and libstdc++ also accept ranges denoted by LegacyForwardIterators as an extension.
Example
#include <iostream> #include <algorithm> #include <vector> int main() { std::vector<int> v{0, 0, 3, -1, 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 -1 0
See also
divides a range of elements into two groups (function template) |
|
(C++20)
|
divides elements into two groups while preserving their relative order (niebloid) |
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