https://github.com/nikouu/fun-weird-nasty-csharp
C# snippets That Make You Go Hmmm...
https://github.com/nikouu/fun-weird-nasty-csharp
csharp dotnet
Last synced: about 1 year ago
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C# snippets That Make You Go Hmmm...
- Host: GitHub
- URL: https://github.com/nikouu/fun-weird-nasty-csharp
- Owner: nikouu
- Created: 2023-12-22T00:49:18.000Z (over 2 years ago)
- Default Branch: main
- Last Pushed: 2024-09-14T04:54:48.000Z (almost 2 years ago)
- Last Synced: 2025-03-28T21:05:46.531Z (over 1 year ago)
- Topics: csharp, dotnet
- Homepage:
- Size: 80.1 KB
- Stars: 4
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# Fun Weird Nasty C#
C# snippets That Make You Go Hmmm...
All snippets are linked to their original creators (or the people I found them from). I don't take any credit, just collating fun bits! Most also have [SharpLab.io](https://sharplab.io/) links so you can see them in action yourself.
## Smallest C#
```csharp
{}
```
[Via nietras](https://nietras.com/2021/10/09/worlds-smallest-csharp-program/)
[SharpLab](https://sharplab.io/#v2:EYLgtghglgdgNAFxAJwK4wD4G8C+Q===)
## It's all Greek
```csharp
using System;
unsafe class Program
{
delegate void bar(int* i);
static Index ƛ(bar β) => default;
static void Main(string[] args)
{
int[] ω = { };
int Ʃ = 42;
int? Φ = 10;
var ϼ = ω;
ϼ=ω[ƛ(β:Δ=>Φ??=ω[^++Ʃ]/Ʃ|*&Δ[-0%Ʃ]>>1^Φ??0!&~(δ:Ʃ,^Φ..).δ)..(1_0>.0?Ʃ:0b1)];
}
}
```
[Via Llewellyn Pritchard](https://twitter.com/leppie/status/1492256050774487047)
[SharpLab](https://sharplab.io/#v2:D4AQTAjAsAUArgOwM4EMBmBTABOHEDssA3rFmVgCYYA2GA5igC7YgAsWARigE4AUAlgkYAqLPwCUAblLkQEAGxYAkgioAPLIGzAXl25ZATcDisAXgB8lDGhRxqjaTHJ5FbLAFkUg3nIAMAbQC6WDx0SOIyZCQOjuSCjAFYgJPAJlhEWAC+9tExQliAlYDJrGCZWWJCAPxYgGXAyRDexVkAbjxYgD/AyQn10eHRLcYJvtr6AFyAKcBmlWVlfb4AegDUc7n+APS5wMIAZCO+ALTeAKRLpqYQMxNl3gCEGwB+vIAtwEO5ADRnAHRv4m/3X2+8EAB9bymN7eMq5IbeDgQcT+TppWBpIA)
## Mutate ReadOnly fields
```csharp
using System;
using System.IO;
Console.WriteLine(Path.DirectorySeparatorChar); // prints '\'
var f = (in char x) => { /* can't modify 'x' here */ };
f = (ref char x) => { x = 'A'; }; // but can here!
f(Path.DirectorySeparatorChar);
Console.WriteLine(Path.DirectorySeparatorChar); // prints 'A'
```
[Via Aleksandr Shvedov](https://twitter.com/controlflow/status/1737788743270965538)
[SharpLab](https://sharplab.io/#v2:EYLgtghglgdgNAFxAJwK4wD4AEBMBGAWACgsAGAAizwDoBJAeQG5jiqBOACgAUIEALagBEoyAKYBjBAHtkATwDKogA4RkvGQGE+qgJSNyAegPklyWAgDO5AOQAdayyIA3VeQBm5ALzkOscuO1kcgAPHS8APnIAb0MAKn8IGGsEcjApABMoN1kbYOtyPlExcljjAF9mIg9vDjEPANdQiOiQrxsAQWt9CsNjYFQU8USCotEAQkc3bl4BYTFJGQVlVXVkLV1K1jxOHn4hEQlpOUUVNSP15D1ekzMYSw7rIA)
## New DateTime formula, *Euclidean affine functions*
```csharp
// Exactly the same as Year, Month, Day properties, except computing all of
// year/month/day rather than just one of them. Used when all three
// are needed rather than redoing the computations for each.
//
// Implementation based on article https://arxiv.org/pdf/2102.06959.pdf
// Cassio Neri, Lorenz Schneiderhttps - Euclidean Affine Functions and Applications to Calendar Algorithms - 2021
internal void GetDate(out int year, out int month, out int day)
{
// y400 = number of whole 400-year periods since 3/1/0000
// r1 = day number within 400-year period
(uint y400, uint r1) = Math.DivRem(((uint)(UTicks / TicksPer6Hours) | 3U) + 1224, DaysPer400Years);
ulong u2 = (ulong)Math.BigMul(2939745, (int)r1 | 3);
ushort daySinceMarch1 = (ushort)((uint)u2 / 11758980);
int n3 = 2141 * daySinceMarch1 + 197913;
year = (int)(100 * y400 + (uint)(u2 >> 32));
// compute month and day
month = (ushort)(n3 >> 16);
day = (ushort)n3 / 2141 + 1;
// rollover December 31
if (daySinceMarch1 >= March1BasedDayOfNewYear)
{
++year;
month -= 12;
}
}
```
[30% optimization of DateTime.GetDate()/.Year/.Month/.Day/.DayOfYear by 'Euclidean affine functions' #72712](https://github.com/dotnet/runtime/pull/72712)
## ReadOnly lists aren't always readonly
```csharp
using System;
using System.Collections.Generic;
var list = new List{1, 2, 3, 4};
IReadOnlyList readonlyList = list;
// error CS1061: 'IReadOnlyList' does not contain a definition for 'Add'...
// readonlyList.Add(5);
// Works as expected
((List)readonlyList).Add(5);
// 5
Console.WriteLine(readonlyList.Count);
```
[Via Nick Chapsas](https://www.youtube.com/watch?v=7hBPI0xYezo&t=203s)
[Great explanation on SO](https://stackoverflow.com/a/49115272)
[SharpLab](https://sharplab.io/#v2:C4LgTgrgdgPgAgJgIwFgBQcAMACOSAsA3OugG4CGY2ANgJYDOw2AvNlAKYDu2AMg8AB5aUYAD4A3kgA02BDIDMM/AF9iadAEkASu3IATAPJRqATz6MhI0djC69Ae2Nn+LGvzXoA9J+zswYeyoAYQBlJEwANiQQbABybTsjU3NBYTFY7Ad2ejZ7JgBjR2ByYWxyTPYAM2FaYFpHbErAuIBBPT1YgDpurx9bfUdk/k62vQAKAFYASg80b2wAdUCAaxzyHPYADwAHdnzgdj10MbGUyzEp/ocnFKmR9smZkjmfCfQ8AE4xq8HnRk6gvZoMAZkA==)
## async async async (async async)
```csharp
async async async(async async) =>
await async;
```
[Via Jared Parsons](https://twitter.com/jaredpar/status/1613615815231934468)
[Explainer from Jared](https://gist.github.com/jaredpar/6706628bfe0098840ce453c1c71098a9)
[SharpLab](https://sharplab.io/#v2:EYLgtghglgdgNAFxFANnAJiA1AHwAIBMAjALABQeADAAR5EB0ASgKYBmKzAxglAPYz0AomCgIA3OSq0GjAK4weYZvQDCvMAAdUzAE4BlXQDconZgGcJFGnQCsl8gGIYslCgjAO1dFDPuO5SQJaPB0uXh10agBvagBfQOoAdwALXWZouPJqbOoEvQQdWABzaKycvABmaQA2aihNFBNRal4NXQgEcOp8wpgigAp0AE8YCBFOakMIHQBKagBeAD5qZ1dLeLIE4dHxjI3K2iCpnQyAshyvEbGTS52bpZWXFEsL19zz8oAWalDOcPR+ik0t0CsUFo9XHA6gpqENweg2BAXAgZmVslE0a8emCzOCEMkfPRttdOC8crELpjXpi8AAOWjVAA8sAQywAsv05hiPm9jpNwTBmIlOWS3ngAJyTeh0/qCxK0Wmcmai154ADs1EoKo2lJ5Cv1MrpCrmDyp5UldPWZwA9NbqAARXiw3iyagqJLJDrUACSAHIwF5eGDUqEAPwJFQxDZnQi0SUgH0AOV4PFYQzUDWYPH4pT1B2AvF4KB9ZgzGg4CGYkQeBVkzBVBzw3wA4lmWGZkZy9jSqk3qAB5GBlitV/p0IJ/BSwWQdPgwLmZMjRsgAbQAgmYRpw2Vnkrx0AAhWSoBE6foIIZtXisfrAY8oU8zGYAXQSRpiPbj1FbCDXiWglZniayz4jovDyqszzkMusZ3ieujkNyFz5vep5dlGn50LUcEProbqhB0zBdg8coiph3wGAg7adguOrlL2FFZoIAAepgaNmMD9CxbEcdQzC0eRILTAgjIACr5IRbIQJwBKCos/ShKw1DiQgknSbJ6RmKplZSTJsD8Wa2RAqEykSTp6n6dQCbehuW5mcwukaQsIHJGBEFPA2vb0ngtQkR5gl/gBg7DlmVZiYFoi6FCKlqXpcn9IZPxsMpEWAXGUVJUpMXmXFmnaQ5FmCqieoXMZ6SialeHWcmqbpuo5ZZnOiVlaZ+WOZZ1m2TAnD2e1grOdQoHgRCUF5gx1CpQAqjAvisMwwX1SO6Dhf+kU6NFvWFcw8mJYpKWrWlEoZXt2UFbl1BabFGnFW8RkhuVlUnNZKiFDwnAQCgNVQGmIUcc192tVdHU+l1PVtVtA1De5ayCZRm25f0Nmbt18NOZdOXXZDrnDZBVpkEAA==)
## async async async (async async) Part 2
```csharp
[async, async] async async async([async, async] (async async, async) async)
=> await async.async;
```
[Via Lucas Trzesniewski](https://twitter.com/Lucas_Trz/status/1613628484315713576)
[SharpLab](https://sharplab.io/#v2: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=)
## Floats are inaccurate
```csharp
using System;
float x = 0.4f;
float y = 0.6f;
Console.WriteLine((double)x + (double)y == 1); // False
Console.WriteLine((float)((double)x + (double)y) == 1); // True
```
[Via Ashley Hauck](https://twitter.com/khyperia/status/1730232117831815322)
[Explainer by Ashley Hauck](https://mas.to/@khyperia/111500086973840518)
[SharpLab](https://sharplab.io/#v2:C4LgTgrgdgPgAgJgIwFgBQAzANgewIbAAEAHoQLyEAMAdACwYDc62+RAnuVdQGyPpxIAnAAphAExwQARlgCmASlIBqQuMkyFHMhSTymaASOEsC80ROlzFhFWsub55HXqA)
## Ensure `finally` with `ThreadAbort`
Note this is for .NET Framework.
```csharp
try {}
finally
{
if (!m_canceled)
{
m_canceled = true;
TimerQueue.Instance.DeleteTimer(this);
}
}
```
[Via Roman Marusyk](https://twitter.com/MarusykRoman/status/1644002015431872514)
[Documentation](https://learn.microsoft.com/en-us/dotnet/api/system.threading.thread.abort?view=net-7.0)
## C# lunar cycle performance
An unsigned number bug in `Environment.TickCount` in a specific situation in a threadpool prevent more threads from being added to the pool.
[Via Kevin Gosse](https://twitter.com/KooKiz/status/1389942946514997248)
[GitHub Issue](https://github.com/dotnet/runtime/issues/51935)
## Dynamic var global using
```csharp
global using var = dynamic;
```
[Via Jared Parsons via Immo Landwerth](https://twitter.com/terrajobst/status/1785375779179893144)
## Amogus
This code is C# version (definitely not as nice) of Python code that returns the "ඞ" character for the Among Us meme.
```csharp
// Python code
// chr(sum(range(ord(min(str(not()))))))
// C# version
var amogus = (char)Enumerable.Range(0, (int)true.ToString().Min()).Sum();
```
[Via @chordbug](https://x.com/chordbug/status/1834642829919781369)