It will only display the value of idx if it is a negative value or if it is greater than 6. Since in line 72 you assign the modulus of six (should be seven, not six), the only possible values for idx are 0, 1, 2, 3, 4 and 5. All these are covered in the switch with return statements that make the code skip line 84.
Also, you could move your cout << idx << endl; above the switch().
Also, there's no need for break; after a return because a return will cause your function to terminate.
Nothing after a return X; instruction is executed anymore, which is why your cout doesn't work in the first place.