Passing dynamic arrays c++

arrayPractice_01.cpp

// elaborated from https://github.com/Headturna/Examples/blob/master/Examples/Example34.cpp 

#include<iostream>

// note arrays always pass by reference, so any change within the function modifies the passed array

void test1(int* (arr), int length) // passing a pointer to a function
{
	for (int i = 0; i < length; i++)
	{
		arr[i] = i * 10;
	}
}

void test2(int* (&arr), int length) // passing a pointer by reference to a function
{
	for (int i = 0; i < length; i++)
	{
		arr[i] = i * 10;
	}
}

void test3(int(arr[]), int length) // passing an array
{
	for (int i = 0; i < length; i++)
	{
		arr[i] = i * 10;
	}
}

int main()
{
	int arrLength = 10;
	int* intArr1 = new int[arrLength];	// create dynamic array; note that arrLength needs not to be const

	std::cout << "initializing intArr1\n";

	for (int i = 0; i < arrLength; i++) // initialize dynamic array intArr1 to 0
	{
		intArr1[i] = 0;
		/**(intArr1 + i) = 0;*/
		std::cout << i << ": " << intArr1[i] << std::endl;
	}

	std::cout << std::endl;

	test1(intArr1, arrLength); // call test1; pass intArr1 a pointer -> test1(int* (arr), int length)

	std::cout << "output after calling test1\n";

	for (int i = 0; i < arrLength; i++)
	{
		std::cout << i << ": " << intArr1[i] << std::endl;
	}

	delete[] intArr1;
	std::cout << std::endl;

	int* intArr2 = new int[arrLength];

	test2(intArr2, arrLength); // call test2; pass intArr2 by as a reference to a pointer -> test2(int* (&arr), int length)

	std::cout << "output after calling test2\n";

	for (int i = 0; i < arrLength; i++)
	{
		std::cout << i << ": " << intArr2[i] << std::endl;
	}

	delete[] intArr2;
	std::cout << std::endl;

	int* intArr3 = new int[arrLength];

	test3(intArr3, arrLength); // call pass intArr3 by pointer as an array -> test3(int (arr[]), int length)

	std::cout << "output after calling test3\n";

	for (int i = 0; i < arrLength; i++)
	{
		std::cout << i << ": " << intArr3[i] << std::endl;
	}

	std::cout << std::endl;

	const int myarrLength = 10; 
	int myStaticArray[myarrLength]{ 0 }; // note that static array requires const myarrLength

	std::cout << "output for static array\n";

	for (size_t i = 0; i < myarrLength; ++i)
	{
		myStaticArray[i] = intArr3[i];
		std::cout << myStaticArray[i] << "\t";
	}

	delete[] intArr3;

	std::cout << std::endl;
}

variations of passing a dynamic array to functions.