Static variable initialized with wrong value

Question

I've defined a function like this

static void
flatten_tree(...)
{
  static int num = 0;
  ...
}

However, when the function is executed, num gets some random value, rather than 0 on the first run. Upon subsequent function calls it behaves as static var should do. Aren't static variables explicitly initialized with zero? What is the proper way to initialize it?

Answer 1

If it's not set to zero the first time it's called then either your C implementation is broken, your debugger is broken, or you've made some other error - I won't comment on which is the most likely scenario :-)

If you really want to see what it's doing, chage your code temporarily to something like:

static void
flatten_tree(...)
{
  static int num = 0;
  printf( "XYZZY DEBUG: initial num is %d\n", num);
  exit(1);

  ...
}