The reverse() Algorithm

 
  #include <algorithm>
  #include <vector>
  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 <char> vc (arr, arr+4); // initialize vc
    reverse(vc.begin(), vc.end());
  }