Answer 1

char dept[] = "HR";

This is an instance of a C-style string - An array of characters with a null-terminator.

In general, if you do not specify the array size, the array will be sized to fit the contents assigned to it. E.g.

int arr[] = {1,2,3};

has size 3.

Going back to C-style strings, we did mention that they are null terminated. So

char dept[] = "HR";

would be of size 3, storing 'H', 'R', '\0'.

You can check the size of an array by printing:

sizeof(dept)/sizeof(dept[0])

The size of the entire array in bytes divided by the size of a single array element in bytes, giving the number of slots of an array.