print(String(Float(2 * (10 / 9))))
Why does this code print "2.0"?
Using a calculator, "2 * (10 / 9)" would equal 2.222222.....
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shallowThought
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@MartinR is this related to the issue that I faced couple weeks ago (I assume that you forgot about it), which is floating point numbers are represented as scientific notations? – Ahmad F Jan 08 '17 at 08:53
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@AhmadF: Sorry, I don't know what issue you are talking of. – But this is unrelated to floating point numbers or scientific notation. `10 / 9` is a integer division and evaluates to `1` in Swift and in many other programming languages. – Martin R Jan 08 '17 at 09:58
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@MartinR Thank you for your response, my issue was how can I count the number of the digits after the "." (on the right side) in floating points, you and Rob told me it is not possible and -thankfully- my question marked as duplicated to [this one](http://stackoverflow.com/questions/588004/is-floating-point-math-broken). – Ahmad F Jan 08 '17 at 10:03
2 Answers
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You are calculating with integer numbers and cast the (integer) result to Float.
Do your calculation with floating point types (Double) instead:
print(String(Float(2.0 * (10.0 / 9.0))))
No need to cast though:
print(2.0 * (10.0 / 9.0))
shallowThought
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2.0 * (10.0 / 9.0) would give your the expected result.
In your case, Swift does the calculations based on Integers first (result = 2), then converts this to a float (result = 2.0) and this into a String (result = "2.0")
To get the correct result, it should read:
print(String(Float(2.0 * (10.0 / 9.0))))
You then could leave out the two type conversations:
print(2.0 * (10.0 / 9.0))
jboi
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