Using Iterators

Using Iterators

Note that pointers in C++ satisfy all of the requirements for iterators, as pointer arithmetic is well defined. In particular, if elts is declared to be an array, elts is a pointer to the first element of the array. Thus if we have:

    const int SIZE = 100;
    double elts[SIZE];
    ...
    sort(elts, elts+SIZE)

works fine.

A useful built-in function is copy that is used to copy portions of one container class to another. Thus if have

    string elts[5] = {``a'', ``b'', ``c'',''d'',''e''};
    vector<string> letters[5];
    copy(elts, elts+5, letters.begin())

copies all 5 elts to letters.

We can define generic operators on containers as in genericPrint.cpp:

#include <iostream>
#include <vector>
using namespace std;

template <typename Container>
void print(const Container & c, ostream & out = cout) {
  typename Container::const_iterator itr;
  for (itr = c.begin(); itr != c.end(); ++itr) {
    out << *itr << " ";
  }
  out << endl;
}

int main() {
  vector<int> vec;
  vec.push_back(12);
  vec.push_back(47);
  print(vec);
  return 0;
}

C++ is smart enough to figure out how to instantiate template function to correct type. Note the extra "typename" is necessary before he name Container when used as a prefix.

Using Iterators