Sort stack using another stack

// C program 
// Sort stack using another stack
#include <stdio.h>
#include <stdlib.h>

// Define stack node
struct StackNode
{
	int element;
	struct StackNode *next;
};
// Define a custom stack
struct MyStack
{
	struct StackNode *top;
	int size;
};
struct MyStack *newStack()
{
	//Make a stack
	struct MyStack *stack = (struct MyStack *) malloc(sizeof(struct MyStack));
	if (stack != NULL)
	{
		//Set node values
		stack->top = NULL;
		stack->size = 0;
	}
	else
	{
		printf("\nMemory overflow when create new stack\n");
	}
}
//Create a new node of stack
struct StackNode *newNode(int element, struct StackNode *next)
{
	//Make a new node
	struct StackNode *node = (struct StackNode *) malloc(sizeof(struct StackNode));
	if (node == NULL)
	{
		printf("\nMemory overflow when create new stack Node \n");
	}
	else
	{
		node->element = element;
		node->next = next;
	}
	return node;
}
int isEmpty(struct MyStack *stack)
{
	if (stack->size > 0 && stack->top != NULL)
	{
		return 0;
	}
	else
	{
		return 1;
	}
}
// Add node at the top of stack
void push(struct MyStack *stack, int element)
{
	// Add stack element
	stack->top = newNode(element, stack->top);
	stack->size++;
}
// return top element of stack
int peek(struct MyStack *stack)
{
	return stack->top->element;
}
// Remove top element of stack
void pop(struct MyStack *stack)
{
	if (isEmpty(stack) == 0)
	{
		struct StackNode *temp = stack->top;
		// Change top element of stack
		stack->top = temp->next;
		// remove previous top
		free(temp);
		temp = NULL;
		stack->size--;
	}
}
// Sort the stack elements by using of another auxiliary stack
void sortStack(struct MyStack *stack)
{
	// Create auxiliary stack
	struct MyStack *auxiliary = newStack();
	int data;
	// Executing the loop until when input element are not empty
	while (isEmpty(stack) == 0)
	{
		// Get the top element of input stack
		data = peek(stack);
		// Remove top of current input stack
		pop(stack);
		if (isEmpty(auxiliary) == 1 || peek(auxiliary) <= data)
		{
			// When stack is empty
			// Or when of auxiliary stack have top element are 
			// less than or equal to pop of current stack element
			// Add data to auxiliary stack
			push(auxiliary, data);
		}
		else
		{
			// In case, pop of stack element is less than top of auxiliary stack then
			// Remove auxiliary top elements until the top elements are not greater to data
			while (isEmpty(auxiliary) == 0 && peek(auxiliary) > data)
			{
				// Add auxiliary stack element to input stack
				push(stack, peek(auxiliary));
				// Add top of auxiliary stack
				pop(auxiliary);
			}
			// Add data to auxiliary stack
			push(auxiliary, data);
		}
	}
	// Add back to insert auxiliary element to input stack
	while (isEmpty(auxiliary) == 0)
	{
		// Add auxiliary stack element to input stack
		push(stack, peek(auxiliary));
		// Add top of auxiliary stack
		pop(auxiliary);
	}
}
// Print element of stack
void printData(struct MyStack *stack)
{
	struct StackNode *temp = stack->top;
	while (temp != NULL)
	{
		// Display element value
		printf("  %d", temp->element);
		temp = temp->next;
	}
	printf("\n");
}
int main()
{
	struct MyStack *stack = newStack();
	// Add the stack element
	push(stack, 4);
	push(stack, 7);
	push(stack, 9);
	push(stack, 1);
	push(stack, 12);
	push(stack, 3);
	push(stack, 8);
	push(stack, 5);
	push(stack, 6);
	push(stack, 10);
	printf("\n Before Sort \n");
	printData(stack);
	// Sort operation
	sortStack(stack);
	printf("\n After Sort \n");
	printData(stack);
	return 0;
}

Output

 Before Sort
  10  6  5  8  3  12  1  9  7  4

 After Sort
  1  3  4  5  6  7  8  9  10  12