How to delete pointers that are passed as arguments in function calls C++

Question

edit: I changed the example and tried to clarify what I'm doing.

I have a recursive function that takes a pointer to an array as an argument, creates a pointer to a smaller array, and calls itself, passing the smaller array as an argument

int ListOfNumbers::recursiveQuickselect(int *array, int arrayLen){
   if(arrayLen > 10){
     int *tempArray;
     tempArray = new int[some value];

     ...edit tempArray....

     return recursiveQuickselect(tempArray, tempArrayLen);
   }
   else{
       //base case:
       sort this small array and return an element from it
   }

When I run valgrind I am told that 1 block is lost in the function recursiveQuickselect.

where do I delete tempArray in this code?

If I delete it before the call then I'm passing nothing into the function

I obviously can't delete it after the return statement.

NOTE: I cannot use vectors, this is a school assignment that does not allow them.

Answer 1

You want to pass the address of a dynamically sized array to a function, but want automatic cleanup of the dynamic memory since you have no way to delete the memory. Like many commented, that's exactly what std::vector does, eg in your example

ListOfNumbers::medianOfFivePivot(int *array, int arrayLen){
   std::vector<int> tempArray(tempArrayLen);

   // ...edit tempArray....

   return getMedian(&tempArray[0], tempArrayLen);

Answer 2

How about you delete the memory in getMedian ? If getMedian is recursive, just delete in the base case.

Or (@Havenard), you can store the value of getMedian() delete the memory and then return the value.

C++ supplies std::vector so you do not have to deal with memory management, why not use those instead?

Answer 3

you should just be able to

delete[] tempArray;

If that doesn't work then I really don't understand the question.

Edit: Place the delete[] line right before return