How to easily make a function round to the nearest hundredth

Question

Hello I am making a calculator app and I need a way to round the answer to the second number

possible duplicate of [Rounding in Swift with round()](http://stackoverflow.com/questions/25513357/rounding-in-swift-with-round) — ahruss, Jul 01 '15 at 03:31

score 4 · Accepted Answer · answered Jul 01 '15 at 03:35

4

If you need to round just for display, you can use either NSNumberFormatter or String formatting capability:

let number = 123.456789

let formatter = NSNumberFormatter()
formatter.minimumFractionDigits = 0
formatter.maximumFractionDigits = 2

formatter.stringFromNumber(number)  // "123.46"
String(format: "%.2f", number)      // "123.46"

answered Jul 01 '15 at 03:35

MirekE

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would I be able to add this onto a label? – Michael Paniccia Jul 01 '15 at 04:57
Sure, for example `label.text = String(format: "%.2f", number)` – MirekE Jul 01 '15 at 05:00

score 1 · Answer 2 · answered Jul 01 '15 at 03:24

1

Double(round(num*100)/100)

Should work. The way this works is first it multiplies by 100, which shifts all of the digits over to the left two places. Then it rounds based on the first decimal digit which is now the thousandths place. Then dividing by 100 again will shift everything to the right two decimal places.

This is the same as if you had just looked at the thousandths place and rounded to the nearest hundredth based on that (which is how a human would do it)

answered Jul 01 '15 at 03:24

ezig

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How do I insert this into a function – Michael Paniccia Jul 01 '15 at 03:52
`func roundToHundreth(num: Double) -> Double { return Double(round(num*100)/100) }` – ezig Jul 01 '15 at 13:59

How to easily make a function round to the nearest hundredth

2 Answers2