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Should You Cache Array.Length and List.Count?

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Every time I see for (var i = 0; i < array.Length; ++i) I wonder if accessing that Length property is slow. Should I cache it? It’s comforting to know that for (int i = 0, len = array.Length; i < len; ++i) is only dealing with local variables except on the first loop. Local variables must be faster, right? Likewise, I wonder the same thing about List<T>.Count. I finally got around to running a test to see if caching these length properties makes any performance difference. The answers might surprise you!

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Enumerables Without the Garbage: Part 7

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Today we’ll wrap up the iterator series by finishing up porting C++’s <algorithm> header. We end up with a library of functions for common LINQ-style algorithms but without any of the garbage creation that slows our games down. Read on for the source and examples!

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Enumerables Without the Garbage: Part 6

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We’re nearing the end of the series to build a no-garbage replacement for System.Linq. Today we tackle functions that work on already-sorted ranges and functions that work on ranges that are in heap order. These include common set operations like “union” and “intersection”. Read on to see how to use them and for the updated library that you can use to eliminate your garbage creation!

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Enumerables Without the Garbage: Part 5

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This week we continue with iterators to get the functionality of IEnumerable without the nasty garbage creation. This week the little iterator library gets support for sorting and binary searching. Read on for the details!

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Enumerables Without the Garbage: Part 4

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Back from a brief break, we pick up this week by finishing up the “modifying sequence operations” with some gems like RandomShuffle and go through the “partitions” category with functions like Partition and IsPartitioned. These are all solid algorithms with a lot of potential uses, so read on to see how to use them with iterators and for the source code that implements them!

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Enumerables Without the Garbage: Part 3

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Continuing the series this week we’ll delve into the iterator functions that modify the sequence. This includes handy tools like Copy, SwapRanges, and Transform. Of course this is all done without creating any garbage! Read on to see how and for the full source code.

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Enumerables Without the Garbage: Part 2

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Last week’s article introduced the concept of iterators as an alternative to the GC-heavy IEnumerable. Today’s article expands the iterator library to include a bunch of more functions to make it useful. Think of these like the extension functions in System.Linq: Any, IndexOf, etc. These have all been tailored to iterators and none of them will create any garbage whatsoever.

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Enumerables Without the Garbage: Part 1

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In C#, just about everything is an IEnumerable. Since LINQ syntax, foreach loops, and the System.Linq namespace are all designed to work with IEnumerable, you’ve got lots of tools to use. Unfortunately, the core of IEnumerable is the GetEnumerator function which usually creates garbage and eventually causes memory fragmentation and GC framerate spikes. Do we simply stop using all of these nice tools? Normally the answer is “yes”, but today’s article shows you another way.

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Iterating Multiple Lists In Order: Part 2

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Last week I presented a problem: how do you iterate over multiple lists of multiple types in the order of some common field? For example, how would you iterate over a list of Player and a list of Enemy by both of their Health fields? In that article I showed two solutions to iterate over two lists in this way. What I didn’t show were any solutions to handle more than two lists. What if you needed to also iterate over a list of NPC? Today’s article discusses how to tackle this problem and ends up with a handy utility class that you can use for your own types no matter how many lists you have. Read on to see how!

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Do Foreach Loops Create Garbage?

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We know that we should reduce the garbage our code produces to lighten the load on Unity’s garbage collector. The trouble is that many of the ways we’re creating garbage are hidden from us. One such way to inadvertently create a lot of garbage is to use a foreach loop… at least that’s what we’ve been told. Do foreach loops really create garbage for all types of arrays, lists, dictionaries, and the rest of the collections? Do they create garbage for every loop or just the first one? Today’s article investigates to put these questions to rest. Are you safe using foreach loops or should you re-write everything to use for. Read on to find out!

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