Binary search with returned index in STL?

Question

I need a binary search function.

I couldn\'t find any function in the standard library that will return the index of the found item, and if it wasn\'t found,

Answer 1

int bin_search (ForwardIterator first, ForwardIterator last, const T& val)
{
  ForwardIterator low;
  low = std::lower_bound(first,last,val);
  if(low!=last && !(val<*low)){
    return (low - first + 1);
  }else{
    return 0;
  }
}