convert to binary using stack C++

I am writing a small program to convert a number into base 2/8/16.

The requirements are to create the stack without using class, just use an array, a pointer to hold subscript and the stack will have push and pop functions including empty and full check.

So the question is how do I create a stack without using class, and where should I implement the calculations in `push()` and print in `pop()` as well as the checkEmpty and checkFull. Thanks

    int main()
    {
    	const int SIZE = 100;
    	int stack[SIZE];
    	int *p; // subscript pointer to the stack
    
    	// assign address of stack to pointer
    	p = stack;
    
    
    	return 0;
    }
    
    // function to insert at the top of stack
    void push (int *p, int stack[], int size, int newData)
    {
    
    }
    
    // function to pop the function
    int pop (int *p, int stack[], int size)
    {
    
    	// return top most element
    }