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std::remove, std::remove_if

From cppreference.com
 
 
 
Defined in header <algorithm>
template< class ForwardIterator, class T >

ForwardIterator remove( ForwardIterator first, ForwardIterator last,

                        const T& value );
(1)
template< class ForwardIterator, class UnaryPredicate >

ForwardIterator remove_if( ForwardIterator first, ForwardIterator last,

                           UnaryPredicate p );
(2)

Removes all elements satisfying specific criteria from the range [first, last). The first version removes all elements that are equal to value, the second version removes all elements for which predicate p returns true.

Removing is done by shifting the elements in the range in such a way that elements to be erased are overwritten. The elements between the old and the new ends of the range have unspecified values. An iterator to the new end of the range is returned. Relative order of the elements that remain is preserved.

Contents

[edit] Parameters

first, last - the range of elements to process
value - the value of elements to remove
p - unary predicate which returns ​true if the element should be removed.

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.
The type Type must be such that an object of type ForwardIterator can be dereferenced and then implicitly converted to Type. ​

[edit] Return value

iterator to the new end of the range

[edit] Complexity

Exactly std::distance(first, last) applications of the predicate.

[edit] Notes

The similarly-named container member functions list::remove, list::remove_if, forward_list::remove, and forward_list::remove_if erase the removed elements.

[edit] Possible implementation

[edit] Example

The following code removes all spaces from a string by moving them to the end of the string and then erasing.

#include <algorithm>
#include <string>
#include <iostream>
int main()
{
    std::string str = "Text with some   spaces";
    str.erase(std::remove(str.begin(), str.end(), ' '),
              str.end());
    std::cout << str << '\n';
}

Output:

Textwithsomespaces

[edit] See also

copies a range of elements omitting those that satisfy specific criteria
(function template) [edit]