Can you 'create' new operators? Like a +++ which would, for example add two to the variable? I tried making a simple program to find the answer for myself. But I failed miserably; I don't know if it's because I'm overlooking something, or you simply cannot do what I'm asking.

Code:
#include <iostream.h>
typedef unsigned short int USHORT;

class addthis
{
public:
	addthis() { val = 0; } 
	~addthis() {}
	addthis(USHORT x) { setVal(x); }
	USHORT getVal() { return val; }
	void setVal(USHORT x) { val = x; }
	addthis operator+++ ();
	addthis operator++ ();
private:
	USHORT val;
}

addthis addthis::operator+++()
{
	val = val+2;
}

addthis addthis::operator++()
{
	val = ++val;
}

int main(void)
{
	addthis ADDTHIS(22);
	cout << ADDTHIS.getVal();
	ADDTHIS+++;
	cout << ADDTHIS.getVal();
	ADDTHIS++;
	cout << ADDTHIS.getVal();
	ADDTHIS.flush();
	cout << "ADDTHIS.getVal();
	SYSTEM("PAUSE");
	return 0;
}
I got numerous errors in this code. I'm not asking for it to be debugged, I would just like to know if I'm implementing the overload of operators properly.