Remove elements from a sequence

Source code

Declaration

template <class ForwardIterator, class T>
ForwardIterator remove(ForwardIterator first, ForwardIterator last,
                       const T& value);

template <class ForwardIterator, class Predicate>
ForwardIterator remove_if(ForwardIterator first, ForwardIterator last,
                          Predicate pred);

template <class InputIterator, class OutputIterator, class T>
OutputIterator remove_copy(InputIterator first, InputIterator last,
                           OutputIterator result, const T& value);

template <class InputIterator, class OutputIterator, class Predicate>
OutputIterator remove_copy_if(InputIterator first, InputIterator last,
                              OutputIterator result, Predicate pred);

Description    The function remove  removes  those elements from the range [ first, last) that are equal to value and returns the location l, the past-the-end iterator .

The function remove_if  removes  those elements from the range [ first, last) that make the predicate pred return true (i.e, a nonzero value) and returns the location l, the past-the-end iterator .

The function remove_copy  copies  all elements from the range [ first, last) to the range [ result, l) , except those that are equal to value, and returns the location l that is the past-the-end iterator  for the resulting sequence.

The function remove_copy_if  copies  all elements from the range [ first, last) to the range [ result, l) , except those that make predicate pred return true (i.e., a nonzero value), and returns the location l that is the past-the-end iterator  for the resulting sequence.

Type requirements

• ForwardIterator must be at least a regular forward iterator .
• InputIterator must be at least an input iterator .
• OutputIterator must be at least an output iterator .
• Predicate must be a function object type that provides int operator()(S), where S is the dereference type of either ForwardIterator for the replace_if  function or InputIterator for the replace_copy_if  function.

Group Mutating sequence operations.

Time complexity Linear.

The number of assignments is the number of elements not removed, at most n, where n is the size of the range [ first, last) .

Space complexity Constant.

Mutative? Yes.

Details These functions are stable; i.e., the elements that remain in the range (ie. [ first, l) for replace  and replace_if , and [ result, l) for replace_copy  and replace_copy_if ) are in the same order as they were in the original range.

Example Select here

Implementation Select here to view source code (Copyright (C) 1994, Hewlett-Packard Company) for this algorithm.