switch statement

Question

alpha is 5

{
case 1
case 2: alpha = 2 + alpha;
break;
case 4: alpha++;
case 5: alpha = alpha * 2;
case 6: alpha = alpha + 5;
break;
default
alpha - -;
}

My question is what happens at ‘case 4’. Does it not suppose to increament if my lecture says the answer is 15 not 17. Or he made some mistakes

Answer 1

nothing till it hits a match , so nothing at 4 , then
first it jumps to case 5 and alpha = 5*2=10, since no break it goes to case 6 too alpha = 10+5= 15, then we have break so
it comes out hence 15

Answer 2

Thank you