std::remove, std::remove_if

From Cppreference

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. Iterator to the new end of the range is returned. Relative order of the elements that remain is preserved.

[edit] Parameters

[edit] Return value

iterator to the new end of the range

[edit] Complexity

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

[edit] Equivalent function

template<class ForwardIterator, class T>
ForwardIterator remove(ForwardIterator first, ForwardIterator last, 
                       const T& value)
{
    ForwardIterator result = first;
    for (; first != last; ++first)
        if (!(*first == value)) {
            *result++ = *first;
        }
    }
    return result;
}

template<class ForwardIterator, class UnaryPredicate>
ForwardIterator remove_if(ForwardIterator first, ForwardIterator last, 
                          UnaryPredicate p)
{
    ForwardIterator result = first;
    for (; first != last; ++first)
        if (!p(*first)) {
            *result++ = *first;
        }
    }
    return result;
}

[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