What if I don't write default in switch case?

Question

int a = 10;
switch(a){
case 0:
    printf(\"case 0\");
    break;
case 1:
    printf(\"case 1\");
    break;
}

Is the above code valid?

If

Answer 1

It's valid not to have a default case.

However, even if you are sure that you will not have any value rather than 1 and 0, it's a good practice to have a default case, to catch any other value (although it is theoretically impossible, it may appear in some circumstances, like buffer overflow) and print an error.