Algorithm
Moves desired elements to the front of a container, and returns an iterator that describes where the sequence of desired elements ends.
None
#include <algorithm>
template <class InputIterator,
class OutputIterator,
class Predicate>
OutputIterator remove_copy_if (InputIterator first,
InputIterator last,
OutputIterator result,
Predicate pred);
The remove_copy_if algorithm copies all the elements referred to by the iterator i in the range [first, last) for which the following condition does not hold: pred(*i) == true. remove_copy_if returns an iterator that points to the end of the resulting range. remove_copy_if is stable, which means that the relative order of the elements in the resulting range is the same as their relative order in the original range.
Exactly last1 - first1 applications of the corresponding predicate are done.
//
// remove.cpp
//
#include <algorithm>
#include <vector>
#include <iterator>
#include <iostream>
using namespace std;
template<class Arg>
struct all_true : public unary_function<Arg, bool>
{
bool operator() (const Arg&) { return 1; }
};
int main ()
{
int arr[10] = {1,2,3,4,5,6,7,8,9,10};
vector<int> v(arr+0, arr+10);
copy(v.begin(),v.end(),
ostream_iterator<int,char>(cout," "));
cout << endl << endl;
//
// Remove the 7.
//
vector<int>::iterator result = remove(v.begin(),
v.end(), 7);
//
// Delete dangling elements from the vector.
//
v.erase(result, v.end());
copy(v.begin(),v.end(),
ostream_iterator<int,char>(cout," "));
cout << endl << endl;
//
// Remove everything beyond the fourth element.
//
result = remove_if(v.begin()+4, v.begin()+8,
all_true<int>());
//
// Delete dangling elements.
//
v.erase(result, v.end());
copy(v.begin(),v.end(),
ostream_iterator<int,char>(cout," "));
cout << endl << endl;
//
// Now remove all 3s on output.
//
remove_copy(v.begin(), v.end(),
ostream_iterator<int>(cout," "), 3);
cout << endl << endl;
//
// Now remove everything satisfying predicate on output.
// Should yield a NULL vector.
//
remove_copy_if(v.begin(), v.end(),
ostream_iterator<int,char>(cout," "),
all_true<int>());
return 0;
}
Program Output
1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 8 9 10 1 2 3 4 1 2 4
If your compiler does not support default template parameters, then you always need to supply the Allocator template argument. For instance, you need to write:
vector<int, allocator<int> >
instead of:
vector<int>
If your compiler does not support namespaces, then you do not need the using declaration for std.
remove, remove_if, remove_copy