Using defined constants in functions and structs without them going blank (Swift)

Question

Ok, so im starting to learn programming using swift and I know more than the basics but I can't figure this out. So if I'm trying to make a function with some stablished constant values and some variables it seems like I can't define constants without them acting like variables. For example, here I want to make a function for the Area of a Circle:

func CircleArea(radius: Int) {
  println(radius*radius*3.1415926)
}

I also tried

struct Circle {
  let pi = 3.1415926
  var radius: Int

  func CircleArea(pi: Int, radius: Int) {
    println(radius*radius*pi)
  }
}

There is a predefined constant M_PI, so you don't have to define your own. — Martin R
– Martin R, Commented Apr 19, 2015 at 9:53

Leo Dabus · Accepted Answer · 2015-04-19 03:47:39Z

1

You can't multiply Int times Double. You need to convert your Int to Double first:

println( Double(radius*radius)*3.1415926 )

func circleArea(radius: Int) -> Double {
    return Double(radius*radius) * M_PI
}

Note: You should name your methods starting with a lowercase letter. For the mathematical pi value you can use M_PI (Double)

edited Apr 19, 2015 at 3:47

answered Apr 19, 2015 at 3:39

Leo Dabus

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1 Comment

Gabe12 Over a year ago

Thanks! i hadn't notice that

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