Sometimes you just want to copy a subset of a defined sequence to another sequence
This subset consists of only those elements that satisfy a particular condition

//: C06:CopyInts2.cpp
// From "Thinking in C++, Volume 2", by Bruce Eckel & Chuck Allison.
// (c) 1995-2004 MindView, Inc. All Rights Reserved.
// See source code use permissions stated in the file 'License.txt',
// distributed with the code package available at www.MindView.net.
// Ignores ints that satisfy a predicate.
#include <algorithm>
#include <cstddef>
#include <iostream>
using namespace std;

// You supply this predicate
bool gt15(int x) { return 15 < x; }

int main() {
  int a[] = { 10, 20, 30 };
  const size_t SIZE = sizeof a / sizeof a[0];
  int b[SIZE];
  int* endb = remove_copy_if(a, a+SIZE, b, gt15);
  int* beginb = b;
  while(beginb != endb)
    cout << *beginb++ << endl; // Prints 10 only
  getchar();
} ///:~

output
10
The remove? Copy? If() function template requires some pointers that are usually used to limit the scope
A user selected decision function is also added

Another variation of copy algorithm

//: C06:CopyStrings2.cpp
// From "Thinking in C++, Volume 2", by Bruce Eckel & Chuck Allison.
// (c) 1995-2004 MindView, Inc. All Rights Reserved.
// See source code use permissions stated in the file 'License.txt',
// distributed with the code package available at www.MindView.net.
// Replaces strings that satisfy a predicate.
#include <algorithm>
#include <cstddef>
#include <iostream>
#include <string>
using namespace std;

// The predicate
bool contains_e(const string& s) {
  return s.find('e') != string::npos;
}

int main() {
  string a[] = {"read", "my", "lips"};
  const size_t SIZE = sizeof a / sizeof a[0];
  string b[SIZE];
  string* endb = replace_copy_if(a, a + SIZE, b,
    contains_e, string("kiss"));
  string* beginb = b;
  while(beginb != endb)
    cout << *beginb++ << endl;
  getchar();
} ///:~

output
kiss
my
lips

Remove? Copy? If() replaces these elements with a fixed value when outputting a sequence
The replace if() algorithm changes the content in the corresponding position of the original sequence instead of sending it to a separate output sequence
Writing data

//: C06:ReplaceStrings.cpp
// From "Thinking in C++, Volume 2", by Bruce Eckel & Chuck Allison.
// (c) 1995-2004 MindView, Inc. All Rights Reserved.
// See source code use permissions stated in the file 'License.txt',
// distributed with the code package available at www.MindView.net.
// Replaces strings in-place.
#include <algorithm>
#include <cstddef>
#include <iostream>
#include <string>
using namespace std;

bool contains_e(const string& s) {
  return s.find('e') != string::npos;
}

int main() {
  string a[] = {"read", "my", "lips"};
  const size_t SIZE = sizeof a / sizeof a[0];
  replace_if(a, a + SIZE, contains_e, string("kiss"));
  string* p = a;
  while(p != a + SIZE)
    cout << *p++ << endl;
  getchar();
} ///:~

output
kiss
my
lips