Re: Is it okay to ask questions about Accelerated C++ exercises here?
swivelhead <jeti...@gmail.com> wrote:
Thanks Daniel. That's good advice. Here's the final result.
I still have the RetrunType template parameter, but I don't know how
to get the type of a container's elements consistently for STL
container or built-in arrays alike.
Check out "iterator_traits" in your best reference. Two of my
favorites are:
http://www.dinkumware.com/manuals/ and
http://www.sgi.com/tech/stl/
Do you remember Comp 1 in college? What you have below is a first
draft. Now that your function works, it's time to refine it.
template<typename ReturnType, typename InputIterator>
ReturnType median2(InputIterator first, InputIterator last)
{
size_t elementTotal = last - first;
if (elementTotal == 0)
throw std::domain_error("median of an empty set");
std::cout << "The element total is " << elementTotal << endl;
// built the temporary container
ReturnType *tempSet = new int[elementTotal];
Get out of the habit of using raw memory. The above can be replaced
with a vector.
// perform insertion sort
for(int i = 0; i < elementTotal; i++)
{
tempSet[i] = first[i];
}
// perform insertion sort
for(int i = 0; i < elementTotal; i++)
{
// grab element value
ReturnType check = tempSet[i];
// while there is a element to the left that is greater than check
for(int j = i; j > 0 && (tempSet[j - 1] > check); --j)
{
// swap the two element values
tempSet[j] = tempSet[j - 1];
tempSet[j - 1] = check;
}
}
Get out of the habit of writing that which already exists in the
language...
You don't need to sort the whole container in order to find out what
the middle one or two would be if it were sorted. Look up
"partial_sort" in your favorite reference.
// recheck order
std::cout << "rechecking order" << std::endl;
for(size_t index = 0;
index < elementTotal;
++index)
{
std::cout << tempSet[index] << std::endl;
}
The above (and the other couts in this function) are inapproprate. If
you feel the need to put them in, then you should make a seperate
function that creates the output you want to examine.
In other words, if you find yourself wanting to double check the
results of an algorithm you wrote, then you should wrap that algoritm
in its own function that returns the results. Don't put debug couts in
the middle of functions.
// sort<ReturnType, ContainerType>(set, elementTotal);
size_t mid = elementTotal / 2;
ReturnType returnValue =
elementTotal % 2 == 0 ? (tempSet[mid] + tempSet[mid - 1]) / 2 :
tempSet[mid];
delete[] tempSet;
return returnValue;
}