public/subjects/mobile-dev/optional-sum

Optional Sum

Instructions

Write a function called optionalSum() that accepts two integer arguments, and an optional integer argument. Return the sum of all the arguments.

Optional parameters

In Dart you can also make function arguments optional, meaning that a function can work even if the optional argument is omitted. If the optional parameter is omitted, it is considered to be null.

Usage

Example of function with optional parameters:

void someFunction(int firstParameter, int secondParameter, [int? optionalParameter]) {
	if (optionalParameter != null) {
		print('${firstParameter}, ${secondParameter}, ${optionalParameter}');
	} else {
		print('${firstParameter}, ${secondParameter}');
	}
}
void main() {

	someFunction(1, 2);
	someFunction(1, 2, 3);
}

• Note: Optional parameters must come after the required parameters.

• Note: You cannot use both optional and named parameters, you should choose only one of them.