cppFilterArrByPredicate

#include <iostream>

int* createArr(int size)
{
    return new int[size];
}

void deleteArr(int* ptr)
{
    delete[] ptr;
}

void printArr(const int* begin, const int* const end)
{
    while (begin != end)
    {
        std::cout << *begin++ << ' ';
    }
    std::cout << '\n';
}

void fillArr(int* begin, const int* const end, int start, int stop)
{
    while (begin != end)
    {
        *begin++ = (rand() % (stop - start) + start);
    }
}


void fillArr(int* begin, const int* const end, int val, bool inc = false)
{

    while (begin != end)
    {
        *begin++ = val;
        val += inc;
    }
}

void addElementToArr(int*& arr, int& size, int element)
{
    int* newArr{ new int[size + 1]{} };

    for (int i{ 0 }; i < size; ++i)
    {
        *(newArr + i) = *(arr + i);
    }
    //delete[] arr;
    arr = newArr;
    ++size;
    *(arr + size - 1) = element;
}

int* filter(int* begin, int* const end, bool(*pred)(int))
{
    int* insertPos{ begin };
    for (; insertPos != end and pred(*insertPos); ++insertPos);
    if (insertPos == end) { std::cout << "Early finish!" << '\n';  return end; }

    begin = insertPos + 1;

    while (begin != end)
    {
        if (pred(*begin))
        {
            *insertPos++ = *begin;
        }
        ++begin;
    }

    return insertPos;
}

bool allElements(int val) { return true; }
bool noElements(int val) { return false; }
bool evenElements(int val) { return val % 2 == 0; }
bool oddElements(int val) { return val % 2 != 0; }
bool greater40(int val) { return val > 40; }

int main()
{
    int arr1Size{ 20 };
    auto arr1{ createArr(arr1Size) };
    fillArr(arr1, arr1 + arr1Size, 10, 50);
    printArr(arr1, arr1 + arr1Size);
    auto filtered{ filter(arr1, arr1 + arr1Size, evenElements) };
    printArr(arr1, filtered);

    auto filtered1{ filter(arr1, filtered, greater40) };
    printArr(arr1, filtered1);

    //auto smallArr{ createArr(filtered - arr1) };


    deleteArr(arr1);
}