Iterating over collections using range-based for loops

In the modern C++, there is a new feature that is augmented to support the for-each technique to iterate over collections. This feature is useful if you want to do something to the elements of a collection or array without caring about the number of elements or the indexes. The syntax of the feature is also simple. Suppose we have an array named arr and we want to iterate each element using the range-based for loop technique; we can use the following syntax:

    for (auto a : arr)
    // Do something with a

So, we can refactor our preceding begin_end.cpp code to use range-based for loop as we can see in the following code:

    /* range_based_for_loop.cpp */
    #include <iostream>

    auto main() -> int
    {
      std::cout << "[range_based_for_loop.cpp]" << std::endl;

      // Declaring an array
      int arr[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};

      // Displaying the array elements
      // using non-member begin() and end()
      std::cout << "Displaying array element using range-based for
        loop";
      std::cout << std::endl;
      for (auto a : arr) std::cout << a << " ";
      std::cout << std::endl;

      return 0;
    }

The syntax we see in the preceding code is simpler now. If we compile the preceding code, we should find no error and, if we run the code, we should see the following output on the console screen:

We now have a new technique to iterate over the collection without caring about the indexes of the collection. We will keep using it in this book.