Error trying to average the elements of a linked list

Question

I want to calculate the average of elements from a linked list:

.h

class List
{
public:
    List() { head = NULL; }
    void insertNode(int);//inserare nod la sfarsitul unei liste
    void printList();//afisare lista
    void deleteNode(int);
    void medie(float);

.cpp

void List::medie(float) {
    int count = 0;
    int sum = 0;
    int media = 0;
    Node* temp3 = head;
    while (temp3 != NULL) {
        count++;
        sum += temp3->val;
        temp3 = temp3->next;
    }
    media = (double)sum / count;
    return media;
}

I received this error:

return value type doesn't match the function type

I don't know how to repair it.

Answer 1

The function is declared with the return type void

void medie(float);

So it means that it returns nothing. However within the function definition there is a return statement with a non-void expression.

return media;

So the compiler issues an error message.

Also the function parameter is not used within the function. Its declaration does not make a sense.

In this statement

media = (double)sum / count;

there is no great sense to cast the variable sum to the type double because the result is assigned to the variable media having the type int.

The function should be declared the following way

double medie() const;

and defined like

double List::medie() const
{
    double sum = 0.0;
    size_t count = 0;

    for ( const Node *temp = head; temp != nullptr; temp = temp->next )
    {
        sum += temp->val; 
        ++count;
    }

    return count == 0 ? 0.0 : sum / count;
}