Why am I getting the Invalid conversion from 'int' to 'int*' error among other errors?

Question

So I'm very new to pointers and pointer syntax, and I've just written this function but have about 5-6 build errors and after looking at the code for a while, I'm still unsure on how to fix them or why they are errors. I'm new to pointers and memory so that is why I am unsure regarding how to fix these bugs and why they are wrong. Thanks for your help it is appreciated it!

int makeFrequency (int data[], int dSize, int *minDataValue, int     *maxDataValue)
{

  findMinAndMax(data, dSize, minDataValue, maxDataValue);

  int fSize = *minDataValue + *maxDataValue; // invalid operands of types 'int' and 'int*' to binary 'operator+' error?

  int frequency = new int [fSize]; //invalid conversion error?

  if (frequency == NULL)
  {
    return NULL;
  }

  for (int i = 0; i <= fSize; i++)
  {
    frequency[i] = 0; // invalid types 'int[int]' for array subscript error?
  }


      for (int i = 0; i <= dSize; i++)
      {
        int j = data[i] - (*minDataValue)+1; // invalid operands of types 'int' and 'int*' to binary 'operator-' error?
        frequency[j] = frequency[j] + 1; // invalid types 'int[int]' for array subscript error?
      }

      return frequency;
    }

int main() {

  int dSize;
  int *ArrayOfInts;

  cout << "How many data values? ";
  cin >> dSize;

  ArrayOfInts = new int [dSize];

  getData(dSize, ArrayOfInts);

  int *frequency, min, max;

  frequency = makeFrequency (ArrayOfInts, dSize, &min, &max); // invalid conversion error?

  if (frequency == NULL) return -1;

  makeHistogram(frequency, min, max);

  delete [] frequency;

  return 0;
}

Answer 1

int frequency = new int [fSize]; //invalid conversion error?

new returns a pointer to the heap-allocated object. When you allocate X , new return an X * .

new X[n] allocates n instances of X and returns a pointer to the first instance of X.

(In all cases, new also invokes the allocated objects' constructors, but this is an irrelevant point here).

new int [fSize];

Therefore, this expression returns an int * .

int frequency

frequency is, obviously an int .

int frequency = new int [fSize];

Putting all of the above together, here you are attempting to assign an int * to an int . That's your conversion error. frequency should be declared as an int * .