The argument type 'int?' can't be assigned to the parameter type 'num'. Dart & Flutter

void printSum({int x = 5, int y = 6, int? k}) {
  int sum = (k != null) ? (x + y) : (x + y + k);
  print(sum);
}

Error: Getting error on :(x + y + k) for variable k
"message": "The argument type ‘int?’ can’t be assigned to the parameter type ‘num’. ",

>Solution :

this is due to the fact that k is nullable (int?), and the ternary expression is trying to use k in an arithmeticc operation where a non-nullable integer is expected.

you should provide a default value for k when it is null or handle the null case properly. One way to do this is by using the null-coalescing operator (??) to provide a default value for k.

  void printSum({int x = 5, int y = 6, int? k}) {
      int sum = (k == null) ? (x + y) : (x + y + k);
      print(sum);
    }