What is the output of the program

#include <iostream>
using namespace std;

int main()
{
   int i = 0;
   for (i=0; i<20; i++)
   {
     switch(i)
     {
       case 0:
         i += 5;
       case 1:
         i += 2;
       case 5:
         i += 5;
       default:
         i += 4;
         break;
     }
     cout << i << \" \";
   }
   return 0;
} 

(A) 5 10 15 20
(B) 7 12 17 22
(C) 16 21
(D) Compiler Error


Answer: (C)

Explanation: Initially i = 0. Since case 0 is true i becomes 5, and since there is no break statement till last statement of switch block, i becomes 16. Now in next iteration no case is true, so execution goes to default and i becomes 21.
In C++, if one case is true switch block is executed until it finds break statement. If no break statement is present all cases are executed after the true case.