Standard C++ Library Class Reference

are not removed is the same as their relative order in the original range.
remove_if does not actually reduce the size of the sequence. It actually operates by: 1) copying
the values that are to be retained to the front of the sequence, and 2) returning an iterator that
describes where the sequence of retained values ends. Elements that are after this iterator are
simply the original sequence values, left unchanged. Here's a simple example:
Say we want to remove all even numbers from the following sequence:
123456789
Applying the remove_if algorithm results in the following sequence:
13579|XXXX
The vertical bar represents the position of the iterator returned by remove_if. Note that the
elements to the left of the vertical bar are the original sequence with the even numbers removed.
The elements to the right of the bar are simply the untouched original members of the original
sequence.
If you want to actually delete items from the container, use the following technique:
container.erase(remove(first,last,value),container.end());
Complexity
Exactly last1 - first1 applications of the corresponding predicate are done.
Example
//
// remove.cpp
//
#include <algorithm>
#include <vector>
#include <iterator>
#include <iostream.h>
template<class Arg>
struct all_true : public unary_function<Arg, bool>
{
bool operator()(const Arg& x){ return 1; }
};
int main ()
{
int arr[10] = {1,2,3,4,5,6,7,8,9,10};
vector<int> v(arr, arr+10);
copy(v.begin(),v.end(),ostream_iterator<int>(cout," "));
cout << endl << endl;