Coding in DART: Use a while loop to count the number of digits in a user inputed number

Question

I have been asked to write a program that uses a while loop to count the number of digits in a user inputed number. I have been watching tutorials and reading every doc I've come across and everything I have tried hasn't worked. I can make it work by converting it to a string and using .length but I have to write it with a while loop. I don't get any error messages, and with all the variations I've tried I just get an infinite printing of 0 or what looks like an infinite counting up. Where am I going wrong with this?

  int num = int.tryParse(stdin.readLineSync());
  int digit = 0;

  while (num > 0) {
    digit +1;
    num / 10;
    print(digit);
  }```