I recently learned (the hard way, as usual) something about the Switch statement in C. I had a part of code which I want executed for all the cases in the switch statement. So I naively put that statement just above the first case statement inside the switch structure.

Take a look at this simplified version of the code:

#include <stdio.h>
int main()
  int b = 100;
  int i = 0;
  switch (i)
    b = 10; // This statement never executes
    case 0:
      printf("b = %d\n", b);
  return 0;

b = 10 is the common code that I want executed for all the values of i. To my surprise, the above program returned an output of 100 and the worst part is gcc does not throw any warnings even with the -Wall option.

Solution is quite simple. Move the b = 10 statement above the switch statement. Don’t know if it is a quirk of the language or if it is expected. I will provide an update if I find any more details.