Can two operator functions be defined in a class?

#include <iostream>
using namespace std;
class List {
	private:
		int x[3] ; 
		int y;

	public :
		void set (int a[3] )
		{
			for ( int j = 0; j< 3; j++)
				x[j] = a[j] ; 
		}
		void sety (int a)
		{
		    y=a;
		}
		
		int operator [] (int k)
		{ 
			if (k <0 || k >= 3)	
          { cout << "out of bound";exit (0);}
			return x[k];
		}
		
		int operator + (List t)
		{
		    int b;
		    for(int i=0;i<3;i++)
		    {
		        
		       b = x[i]+t.y; 
		       return b;
		    }
		}
}; 
////////////////////////////////////////////////////////
int main()
{
	List ob ;
	List ob1;
	
	int a[3] = {10, 11, 12};
	
	ob1.sety(3);	
	ob.set (a);
	
	cout << ob[0] << endl;   //10
	cout << ob[1] << endl;   //11
	cout << ob[2] << endl;   //12
	cout << ob[3];    
	for(int i=0;i<3;i++)
	{
	     cout<