void foo(vector<int> *a, unsigned int i = 0, unsigned int j = 0)
{
	if (j == 0)
	{
		j = a->size();
	}
	for (; i < j; i++)
	{
	}
}

void foo(vector<int> *a, vector<int>::iterator i = a->begin(), vector<int>::iterator j = a->end())
{
	for (; i < j; i++)
	{
	}
}

void foo(vector<int> *a, vector<int>::iterator i, vector<int>::iterator j)
{
//...
}
void foo(vector<int> *a)
{
    foo(a, a->begin(), a->end());
}