On Fri, Aug 20, 2010 at 5:22 PM, B Hart wrote:
well assuming an unsigned int array size of 5 what do you suggest for a
reasonably good and fast hash?
I was hoping that I could use the built in hash w/o having to invent one.
boost::hash is actually very nicely extensible. It works with a
number of containers (I was surprised it didn't support boost::array
(or std::array) out of the box), and adding support for something like
boost::array is pretty trivial. See below:
#include
#include
#include
typedef boost::array Array;
namespace boost {
template
std::size_t hash_value(const boost::array& arr)
{
return boost::hash_range(arr.begin(), arr.end());
}}
int main(int argc, char* argv[])
{
Array arr1 = {1000, 3344455, 12455222, 8832232, 1234};
Array arr2 = {2000, 4344455, 22455222, 16832232, 2345};
boost::unordered_set<Array> mySet;
mySet.insert(arr1);
assert(mySet.find(arr2) == mySet.end() && "Found wrong array");
assert(mySet.find(arr1) != mySet.end() && "Not finding correct array");
return 0;
}
HTH,
Nate
