Is this Bubble Sort correct?

Question

People I’m reading book "Programming Principles and Practice using c++ (2nd Edition)" from C++ creator. There is an exercise there at the very beginning talking to do a program that sorts the data numbers. I did it using Bubblesort, burned a lot of neurons doing more I think I got. I wanted to know if he has any error or some situation that wrong, I did some tests and it seems to work. Thank you.

Code below.

#include <iostream>

using namespace std;

void bubbleSort(int * my_integer_array_pointer /*pointer to original array*/,unsigned int array_size)
{
    int tempChanger = 0;
    unsigned int Swaps = 0;
    unsigned int i = 0;


    for (i = 0; i < (array_size -1); i++) //iterate "my_integer_array_pointer", "array_size-1" times
    {
        if (*(my_integer_array_pointer+i) > *(my_integer_array_pointer+i+1)) // if left number is greater than right number, swapp then
        {
            tempChanger = *(my_integer_array_pointer+i);
            *(my_integer_array_pointer+i) = *(my_integer_array_pointer+i+1);
            *(my_integer_array_pointer+i+1) = tempChanger;
            Swaps++; //count the number of swapped numbers
        }
    }
    if (Swaps > 0) // if swap more than 0 times, need to iterate list again
    {
        bubbleSort(my_integer_array_pointer,array_size);
    }
    /*
    else = list is already sorted, stop function.
    */
}

int main()
{
    cout << "Please type the amount of numbers you want to sort:" << endl;
    int my_integer_array_size;
    cin >> my_integer_array_size;
    int my_integer_array[my_integer_array_size] = {};

    for (int i = 0; i < my_integer_array_size; i++) //iterator used to assign a value to each element of "my_integer_array" with "cin"
    {
       cout << "Please type the " << i+1 << " number" << endl;
       cin >> my_integer_array[i];
    }

    cout << endl;
    bubbleSort(my_integer_array,my_integer_array_size);

    cout << "The ordered array is below :" << endl;
    for (unsigned int i = 0; i < sizeof(my_integer_array) / sizeof(int); i++) //iterator to show the results
    {
        cout << my_integer_array[i] << endl;
    }

    return 0;
}

Answer 1

Your code is correct, implemented well the Bubble Sort, but take great care in the vector declaration, because as you did can lead to a number of errors. Remember that when binary code (the result of copying) is executed the memory separation for each variable (based on the type of each one) is done before data entry or anything else. So pay close attention to this detail, because defining the size of the vector by means of a variable that will store the size desired by the user is a very risky practice, since it is not possible to know, before the execution, the contents of the memory spaces reserved for my_integer_array_size and with this can happen to separate a vector smaller than the size that the user will type.

But we have a solution for everything. To use a vector with variable size, just as you did, you need to use dynamic memory artifices, change little and does not disturb anything your logic:

#include <iostream>

using namespace std;

void bubbleSort(int * my_integer_array_pointer /*pointer to original array*/,unsigned int array_size)
{
    int tempChanger = 0;
    unsigned int Swaps = 0;
    unsigned int i = 0;


    for (i = 0; i < (array_size -1); i++) //iterate "my_integer_array_pointer", "array_size-1" times
    {
        if (*(my_integer_array_pointer+i) > *(my_integer_array_pointer+i+1)) // if left number is greater than right number, swapp then
        {
            tempChanger = *(my_integer_array_pointer+i);
            *(my_integer_array_pointer+i) = *(my_integer_array_pointer+i+1);
            *(my_integer_array_pointer+i+1) = tempChanger;
            Swaps++; //count the number of swapped numbers
        }
    }
    if (Swaps > 0) // if swap more than 0 times, need to iterate list again
    {
        bubbleSort(my_integer_array_pointer,array_size);
    }
    /*
    else = list is already sorted, stop function.
    */
	//return my_integer_array_pointer;
}

int main()
{
    cout << "Please type the amount of numbers you want to sort:" << endl;
    int my_integer_array_size;
    cin >> my_integer_array_size;
    int * my_integer_array;

	my_integer_array= new int [my_integer_array_size]; //ALOCAÇÃO DINÂMICA DE MEMÓRIA PARA SEU VETOR

    for (int i = 0; i < my_integer_array_size; i++) //iterator used to assign a value to each element of "my_integer_array" with "cin"
    {
       cout << "Please type the " << i+1 << " number" << endl;
       cin >> my_integer_array[i];
    }

    cout << endl;
    bubbleSort(my_integer_array,my_integer_array_size);

    cout << "The ordered array is below :" << endl;
	//AGORA COM O TAMANHO CONHECIDO E JÁ DEFINIDO PODE-SE USAR A VARIAVEL COM O TAMANHO ESCOLHIDO PELO USUÁRIO COMO CONDIÇÃO DE PARADA DO for
    for (unsigned int i = 0; i < my_integer_array_size; i++) //iterator to show the results 
    {
        cout << my_integer_array[i] << endl;
    }
	delete [] my_integer_array; //IMPORTANTE!! SEMPRE QUE ALOCAR MEMORIA DINAMICAMENTE LEMBRE-SE DE LIBERAR A MESMA AO FINAL DA EXECUÇÃO DO CÓDIGO
    return 0;
}