Question

I can’t achieve rounding a float with the common 0.5 rule.
Let’s be precise… How may I make such rounds :

• x.x2 -> x.x
• x.x5 -> x.x (or x.x+1 would be good also)
• x.x6 -> x.x+1

So for example :

• 1.12 -> 1.1

• 1.22 -> 1.2

• 1.15 -> 1.1 (or 1.2 woudl be good also)

• 1.25 -> 1.2 (or 1.3 woudl be good also)

• 1.16 -> 1.2

• 1.26 -> 1.3

I tried those methods (perhaps in a wrong way) :

• NSNumberFormatter
• NSDecimalNumber
• …

But nothing can give that result. I always get some x.x99999999 results, or badly rounded ones (too high, to low, or on even numbers when the rounded number should come on the upper one).

Answer 1

Try this one:

round(x * 10.0f) / 10.0f