如何在不指定可选参数值的情况下迅速调用以下函数？

Question

In swift it is allowed to have parameters in functions with default values, and it is allowed to have parameters without external names. But, what happens when I combine them? For example, in the following code:

func foo (a: Int, b: Int = 0, _ c: Int) {
    print(a + b + c)
}

Is there any way of call the function foo without specifying a value for parameter b ?

Answer 1

No you can't. That's why Apple recommends in the Swift book to place parameters with default values at the end of the parameters list:

Answer 2

You should have the default parameters at the end of the parameter list.

func foo (a: Int, c: Int, b: Int = 0) {    //put your parameter with default value at the end
    print(a + b + c)
}
//you don't need to specifying a value for parameter b
foo(10, 11)  //21