I'm trying to make a math app with different equations and formulas but I'm trying to circle sector but i just wanted to try to divide the input value by 360 but when I do that it only says 0 unless the value is over 360. I have tried using String, Double and Float with no luck I don't know what I'm doing is wrong but down here is the code. I'm thankful for help but I have been sitting a while and searched online for an answer with no result I might have been searching with the wrong search.
if graderna.text == ""{
}
else{
var myInt: Int? = Int(graderna.text!) // conversion of string to Int
var myInt2: Int? = Int(radien.text!)
let pi = 3.1415926
let lutning = 360
let result = (Double(myInt! / lutning) * Double(pi))
svar2.text = "\(result)"
}
Your code is performing integer division, taking the integer result and converting it to a double. Instead, you want to convert these individual integers to doubles and then do the division. So, instead of
let result = (Double(myInt! / lutning) * Double(pi))
You should
let result = Double(myInt!) / Double(lutning) * Double(pi)
Note, Double already has a .pi constant, so you can remove your pi constant, and simplify the above to:
let result = Double(myInt!) / Double(lutning) * .pi
Personally, I’d define myInt and lutning to be Double from the get go (and, while we’re at it, remove all of the forced unwrapping (with the !) of the optionals):
guard
let text = graderna.text,
let text2 = radien.text,
let value = Double(text),
let value2 = Double(text2)
else {
return
}
let lutning: Double = 360
let result = value / lutning * .pi
Or, you can use flatMap to safely unwrap those optional strings:
guard
let value = graderna.text.flatMap({ Double($0) }),
let value2 = radien.text.flatMap({ Double($0) })
else {
return
}
let lutning: Double = 360
let result = value / lutning * .pi
(By the way, if you’re converting between radians and degrees, it should be 2π/360, not π/360.)
You are dividing an Int by an Int.
Integer division rounds to the nearest integer towards zero. Therefore for example 359 / 360 is not a number close to 1, it is 0. 360 / 360 up to 719 / 360 equals 1. 720 / 360 to 1079 / 360 equals 2, and so on.
But your use of optionals is atrocious. I'd write
let myInt = Int(graderna.text!)
let myInt2 = Int(radien.text!)
if let realInt = myInt, realInt2 = myInt2 {
let pi = 3.1415926
let lutning = 360.0
let result = Double (realInt) * (pi / lutning)
svar2.text = "\(result)"
}
In the line let result = (Double(myInt! / lutning) * Double(pi)) you cast your type to double after dividing two integers so your result will always be zero. You have to make them doubles before division.
let result = (Double(myInt!) / Double(lutning)) * Double(pi))
If you want the value should be correct, then try as
let division = ((Float(V1) / Float(V2)) * Float(pi))
Related
This question already has answers here:
How to truncate decimals to x places in Swift
(10 answers)
Closed 3 years ago.
I am new with swift and I need help. I want to get first two digits after the decimal point, for example -
1456.456214 -> 1456.45
35629.940812 -> 35629.94
without rounding the double to next one.
Try the below code
let num1 : Double = 1456.456214
let num2 : Double = 35629.940812
let numberFormatter = NumberFormatter()
numberFormatter.minimumFractionDigits = 2
numberFormatter.maximumFractionDigits = 2
numberFormatter.roundingMode = .down
let str = numberFormatter.string(from: NSNumber(value: num1))
let str2 = numberFormatter.string(from: NSNumber(value: num2))
print(str)
print(str2)
Output
1456.45
35629.94
To keep it a double you can do
let result = Double(Int(value * 100)) / 100.0
or, as #vacawama pointed out, use floor instead
let result = floor(value * 100) / 100
extension Double {
func truncate(places : Int)-> Double
{
return Double(floor(pow(10.0, Double(places)) * self)/pow(10.0, Double(places)))
}
}
and use this like as;
let ex: Double = 35629.940812
print(ex.truncate(places: 2)) //35629.94
let ex1: Double = 1456.456214
print(ex1.truncate(places: 2)) //1456.45
When I got two numbers, like 5.085 and 70.085. My code rounds the first number to 5.09, but the second one it goes to 70.08. For some reason, when making let aux1 = aux * 100 the value goes to 7008.49999999. Any one have the solution to it?
Here is my code:
let aux = Double(value)!
let aux1 = aux * 100
let aux2 = (aux1).rounded()
let number = aux2 / 100
return formatter.string(from: NSNumber(value: number))!
If you want to format the Double by rounding it's fraction digits. Try't:
First, implement this method
func formatDouble(_ double: Double, withFractionDigits digits: Int) -> String{
let formatter = NumberFormatter()
formatter.maximumFractionDigits = digits
let string = formatter.string(from: (NSNumber(floatLiteral: double)))!
return string
/*if you want a Double instead of a String, change the return value and uncomment the bellow lines*/
//let number = formatter.number(from: string)!
//return number.doubleValue
}
after, you can call't that way
let roundedNumber = formatDouble(Double(value)!, withFractionDigits: 2)
heightInM = ((Double(heightInFeetText.text!)! * 30.48) + (Double(heightInInchText.text!)! * 2.54))/100
output = Double(weightInKgText.text!)! / (heightInM * heightInM)
bmiOutput.text = String(output)
How can I format double value with 2 decimal points?
Just use stringWithFormat API, add specify how many digits would you like to see.
Example:
let floatValue = 2.333123211
let output = String(format: "%0.2f", floatValue) // prints 2.33
In your case:
bmiOutput.text = String(format: "%0.2f", output)
What's the best way to create a single Float value from two Ints? I have two vars:
let int1 = 165
let int2 = 5
I'm trying to combine them into a Float with the value 165.5.
Float to Int
Two approaches.
You can concatenate them into a String and pass that to a Float initializer:
let float1 = Float("\(int1).\(int2)")
Or you can divide int2 by 10 and add int1:
let float2 = Float(int1) + Float(int2)/10
Int to Float
If you want to go back, you can again use strings:
let float : Float = 165.5
let intArray = String(float)
.characters
.split(".")
.map { Int(String($0))! }
intArray[0] // 165
intArray[1] // 5
But it's simpler to use math:
let (int1, int2) = (Int(float), (float - floor(float)) * 10)
How can I convert this to Int? I've tried using the initializer: Int(), using the round method.. All of them generates an error. In this case the one I get is: "float is not convertible to int"
let CirclePoints = 84
let PI = 3.14159
let radius: Double!
let xBase: Int!
let yBase: Int!
var xPos = Int()
var yPos = Int()
xPos = round(xBase + radius * cos((PI / 10) * circlePoint))
I'd recommend converting all of your values to double since that is what the round function takes. The round function also returns a double, so you'll have to convert the result of round() into an Int to store it in xPos.
xPos = Int(round(Double(xBase) + Double(radius) * cos((PI / 10) * Double(circlePoint))))
Note that the conversion process here is actually creating new double values from the variables, not changing those variables.