std::remove_copy, std::remove_copy_if
Defined in header <algorithm>
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(1) | ||
template< class InputIt, class OutputIt, class T > OutputIt remove_copy( InputIt first, InputIt last, OutputIt d_first, |
(until C++20) | |
template< class InputIt, class OutputIt, class T > constexpr OutputIt remove_copy( InputIt first, InputIt last, OutputIt d_first, |
(since C++20) | |
template< class ExecutionPolicy, class ForwardIt1, class ForwardIt2, class T > ForwardIt2 remove_copy( ExecutionPolicy&& policy, ForwardIt1 first, ForwardIt1 last, |
(2) | (since C++17) |
(3) | ||
template< class InputIt, class OutputIt, class UnaryPredicate > OutputIt remove_copy_if( InputIt first, InputIt last, OutputIt d_first, |
(until C++20) | |
template< class InputIt, class OutputIt, class UnaryPredicate > constexpr OutputIt remove_copy_if( InputIt first, InputIt last, OutputIt d_first, |
(since C++20) | |
template< class ExecutionPolicy, class ForwardIt1, class ForwardIt2, class UnaryPredicate > ForwardIt2 remove_copy_if( ExecutionPolicy&& policy, ForwardIt1 first, ForwardIt1 last, |
(4) | (since C++17) |
Copies elements from the range [first, last)
, to another range beginning at d_first
, omitting the elements which satisfy specific criteria. Source and destination ranges cannot overlap.
value
.p
returns true.policy
. This overload only participates in overload resolution if std::is_execution_policy_v<std::decay_t<ExecutionPolicy>> is trueParameters
first, last | - | the range of elements to copy |
d_first | - | the beginning of the destination range. |
value | - | the value of the elements not to copy |
policy | - | the execution policy to use. See execution policy for details. |
Type requirements | ||
-InputIt must meet the requirements of LegacyInputIterator.
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-OutputIt must meet the requirements of LegacyOutputIterator.
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-ForwardIt1, ForwardIt2 must meet the requirements of LegacyForwardIterator.
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-UnaryPredicate must meet the requirements of Predicate.
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Return value
Iterator to the element past the last element copied.
Complexity
Exactly last - first
applications of the predicate.
For the overloads with an ExecutionPolicy, there may be a performance cost if ForwardIt1
's value_type is not MoveConstructible.
Exceptions
The overloads with a template parameter named ExecutionPolicy
report 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.
Possible implementation
First version |
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template<class InputIt, class OutputIt, class T> OutputIt remove_copy(InputIt first, InputIt last, OutputIt d_first, const T& value) { for (; first != last; ++first) { if (!(*first == value)) { *d_first++ = *first; } } return d_first; } |
Second version |
template<class InputIt, class OutputIt, class UnaryPredicate> OutputIt remove_copy_if(InputIt first, InputIt last, OutputIt d_first, UnaryPredicate p) { for (; first != last; ++first) { if (!p(*first)) { *d_first++ = *first; } } return d_first; } |
Example
The following code outputs a string while erasing the spaces on the fly.
#include <algorithm> #include <iterator> #include <string> #include <iostream> int main() { std::string str = "Text with some spaces"; std::cout << "before: " << str << "\n"; std::cout << "after: "; std::remove_copy(str.begin(), str.end(), std::ostream_iterator<char>(std::cout), ' '); std::cout << '\n'; }
Output:
before: Text with some spaces after: Textwithsomespaces
See also
removes elements satisfying specific criteria (function template) | |
(C++11) |
copies a range of elements to a new location (function template) |
(C++11) |
copies a range dividing the elements into two groups (function template) |