使用指针在函数内的数组中添加/删除元素

I am trying to figure this problem out. This is for a project and our instructor requires this header. I got the check function working properly but adding when adding to the array we must use a pointer. My understanding is that we should copy this array to another array and replace the pointer. For example Array1 {1,2,3} then copy it to Array2 {1,2,3,4} then add 4 to expand the array. Unfortunately everything I have found researching.. vectors and other functions would be better suited for this task but we are required to only use the pointer and the size to resize and add the element.I am trying to figure this problem out. This is