Another useful STL algorithm is reverse(). This algorithm reverses the order of elements in a specified sequence. reverse() takes two iterators that mark the sequence’s beginning and end, respectively. Here is an example of reversing the order of a char array:

   #include   #include   using namespace std;  int main()  {    char arr[4] = {'a','b','c','d'};    reverse(arr, arr+4);  // arr is now "dcba"  }

Remember that the second argument of reverse() must point one element past the array’s bounds. Here’s an example of applying reverse() to a vector object:

   int main()  {    char arr[]= {'a','b','c','d'};    vector  vc (arr, arr+4); // initialize vc    reverse(vc.begin(), vc.end());  }