Queue<T>: why set GrowFactor to 200 and divide by 100?

[chukunx]

hi guys, this isn't an issue, but just me being curious about a configuration setup in Queue<T> class. may i ask why do we want to double the size of array by initiating the GrowFactor as 200 and multiplying the original size by GrowFactor / 100 here? what's the downside of using 2 directly? thanks.
https://github.com/dotnet/corefx/blob/bca44089343cf14cffd3cb0982b7e209692f6731/src/System.Collections/src/System/Collections/Generic/Queue.cs#L188

[Wraith2]

Guessing here, if you use 100 as the base you avoid using a float to store fractional growth factors and end up with an integer division which is easier/faster than float division. If that's the case then it feels like a development setup so someone can test various growth factors and perhaps not something that is needed in release builds since GrowthFactor is constant.

[chukunx]

ah i see, it make sense. i evaluated the statement in a wrong order as _array.Length * (GrowFactor / 100), with which the fractional growth wouldn't work. but yes as you mentioned, the GrowthFactor can be directly set to a desired constant value here.