C# .NET Validate Drive Letter with compiler optimization aggressive in-lining for large fall-through case statements

Here's a surprise,  range operator is beaten by a large set of serial cases statements! 

In the below code example which validates a drive letter,  by 

using System.Runtime.CompilerServices;

you can adorn the case-statement method to be compiled with  

[MethodImplAttribute(MethodImplOptions.AggressiveOptimization )] and/or

[MethodImplAttribute(MethodImplOptions.AggressiveInlining)]

to surprising results.  I was surprised by v6. v5 and v6 win on alternative runs.

Full documentation here - https://docs.microsoft.com/en-us/dotnet/api/system.runtime.compilerservices.methodimploptions

Source Code

using System;
using System.Diagnostics;
using System.Runtime.CompilerServices;
					
public static class Program
{
	 //Fri 30-Oct-20 2:17pm metadataconsulting.ca 
	 //https://metadataconsulting.blogspot.com/2020/10/C-NET-Validate-Drive-Letter-with-compiler-optimization-aggressive-in-lining-for-large-fall-through-case-statements.html
	 //-> this method does not exist on the interwebs, trivial?
	 //-> fun with compiler switches to optimize case statements 
	
	 public static bool isValidDriveLetter(this string drivewithcolon)
	 {
		 
		 if (drivewithcolon.Length == 2 && drivewithcolon[1] == ':')
		 {
			 drivewithcolon = drivewithcolon.ToUpper();
			 // this is surprisingly faster than the equivalent if statement
			 switch (drivewithcolon[0])
			 {
				 case 'A':
				 case 'B':
				 case 'C':
				 case 'D':
				 case 'E':
				 case 'F':
				 case 'G':
				 case 'H':
				 case 'I':
				 case 'J':
				 case 'K':
				 case 'L':
				 case 'M':
				 case 'N':
				 case 'O':
				 case 'P':
				 case 'Q':
				 case 'R':
				 case 'S':
				 case 'T':
				 case 'U':
				 case 'V':
				 case 'W':
				 case 'X':
				 case 'Y':
				 case 'Z':
					 return true;
				 default:
					 return false;
			 }
		 }
		 else
			 return false; 

	 }
     //range operator	
	 public static bool isValidDriveLetterV2(this string drivewithcolon)
	 {
		 		 
		 if (drivewithcolon.Length == 2 && drivewithcolon[1] == ':')
		 {
			 drivewithcolon = drivewithcolon.ToUpper();
			 if (drivewithcolon[0] >= 'A' && drivewithcolon[0] <= 'Z') 
			 	return true;
			 else 
				 return false; 
		 }
		 else
			 return false; 

	 }
	
	 [MethodImplAttribute(MethodImplOptions.AggressiveInlining)]
	 public static bool isValidDriveLetterV3(this string drivewithcolon)
	 {
		 
		 if (drivewithcolon.Length == 2 && drivewithcolon[1] == ':')
		 {
			 drivewithcolon = drivewithcolon.ToUpper();
			 // this is surprisingly faster than the equivalent if statement
			 switch (drivewithcolon[0])
			 {
				 case 'A':
				 case 'B':
				 case 'C':
				 case 'D':
				 case 'E':
				 case 'F':
				 case 'G':
				 case 'H':
				 case 'I':
				 case 'J':
				 case 'K':
				 case 'L':
				 case 'M':
				 case 'N':
				 case 'O':
				 case 'P':
				 case 'Q':
				 case 'R':
				 case 'S':
				 case 'T':
				 case 'U':
				 case 'V':
				 case 'W':
				 case 'X':
				 case 'Y':
				 case 'Z':
					 return true;
				 default:
					 return false;
			 }
		 }
		 else
			 return false; 

	 }	
	
	 [MethodImplAttribute(MethodImplOptions.AggressiveOptimization)]
	 public static bool isValidDriveLetterV4(this string drivewithcolon)
	 {
		 
		 if (drivewithcolon.Length == 2 && drivewithcolon[1] == ':')
		 {
			 drivewithcolon = drivewithcolon.ToUpper();
			 // this is surprisingly faster than the equivalent if statement
			 switch (drivewithcolon[0])
			 {
				 case 'A':
				 case 'B':
				 case 'C':
				 case 'D':
				 case 'E':
				 case 'F':
				 case 'G':
				 case 'H':
				 case 'I':
				 case 'J':
				 case 'K':
				 case 'L':
				 case 'M':
				 case 'N':
				 case 'O':
				 case 'P':
				 case 'Q':
				 case 'R':
				 case 'S':
				 case 'T':
				 case 'U':
				 case 'V':
				 case 'W':
				 case 'X':
				 case 'Y':
				 case 'Z':
					 return true;
				 default:
					 return false;
			 }
		 }
		 else
			 return false; 

	 }	
	
	
	 [MethodImplAttribute(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
	 public static bool isValidDriveLetterV5(this string drivewithcolon)
	 {
		 
		 if (drivewithcolon.Length == 2 && drivewithcolon[1] == ':')
		 {
			 drivewithcolon = drivewithcolon.ToUpper();
			 // this is surprisingly faster than the equivalent if statement
			 switch (drivewithcolon[0])
			 {
				 case 'A':
				 case 'B':
				 case 'C':
				 case 'D':
				 case 'E':
				 case 'F':
				 case 'G':
				 case 'H':
				 case 'I':
				 case 'J':
				 case 'K':
				 case 'L':
				 case 'M':
				 case 'N':
				 case 'O':
				 case 'P':
				 case 'Q':
				 case 'R':
				 case 'S':
				 case 'T':
				 case 'U':
				 case 'V':
				 case 'W':
				 case 'X':
				 case 'Y':
				 case 'Z':
					 return true;
				 default:
					 return false;
			 }
		 }
		 else
			 return false; 

	 }	

	[MethodImplAttribute(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
	public static bool isValidDriveLetterV6(this string drivewithcolon)
	 {
		 if (drivewithcolon.Length == 2 && drivewithcolon[1] == ':')
		 {
			 drivewithcolon = drivewithcolon.ToUpper();		 
			 if (drivewithcolon[0] >= 'A' && drivewithcolon[0] <= 'Z') 
			 	return true;
			 else 
				 return false; 
		 }
		 else
			 return false; 

	 }
 	
	public static void Main()
	{
	    bool v1,v2,v3,v4,v5,v6 = false;  

		Stopwatch sw = new Stopwatch(); 

		sw.Start();
		v1= "Z:".isValidDriveLetter(); 
		sw.Stop();
		Console.WriteLine("is Z: valid drive letter ?{0}, v1 in {1} ticks.",v1.ToString(), sw.ElapsedTicks);
		
		sw.Reset(); 
		sw.Start();
		v2= "Z:".isValidDriveLetterV2(); 
		sw.Stop();
		Console.WriteLine("is Z: valid drive letter ?{0}, v2 in {1} ticks.",v2.ToString(), sw.ElapsedTicks);
	
	    sw.Reset(); 
		sw.Start();
		v3= "Z:".isValidDriveLetterV3(); 
		sw.Stop();
		Console.WriteLine("is Z: valid drive letter ?{0}, v3 in {1} ticks.",v3.ToString(), sw.ElapsedTicks);
	
	    sw.Reset(); 
		sw.Start();
		v4= "Z:".isValidDriveLetterV4(); 
		sw.Stop();
		Console.WriteLine("is Z: valid drive letter ?{0}, v4 in {1} ticks.",v4.ToString(), sw.ElapsedTicks);
	
		sw.Reset(); 
		sw.Start();
		v5= "Z:".isValidDriveLetterV5(); 
		sw.Stop();
		Console.WriteLine("is Z: valid drive letter ?{0}, v5 in {1} ticks.",v5.ToString(), sw.ElapsedTicks);
	
		sw.Reset(); 
		sw.Start();
		v6= "Z:".isValidDriveLetterV6(); 
		sw.Stop();
		Console.WriteLine("is Z: valid drive letter ?{0}, v6 in {1} ticks.",v6.ToString(), sw.ElapsedTicks);
		
		
	}
}

Phishing Email from Paisley Hutchinson with subject Security Alert. Your accounts were hacked by a criminal group.

For the record, this is an Paisley Hutchinson phishing email attempt that is recently going around, with subject "Security Alert. Your accounts were hacked by a criminal group." What to do?  Report them, goto bottom of page. 

From : Paisley Hutchinson <support@algotrack.in>  Subject : Security Alert. Your accounts were hacked by a criminal group. Hello! I am a professional coder and I hacked your device's OS when you visited adult website. I've been watching your activity for a couple of months. If you don't understand what I am talking about I can explain... My trojan malware lets me get access to my victim's system. It is multiplatform software with hVNC that can be installed on phones, PC and even TV OS... It doesn't have any AV's detects because it is encrypted and can't be detected becaause I update it's signatures every 4 hour. I can turn on your camera, save your logs and do everything that I want and you won't notice anything. Now I have all your contacts, sm data and all logs from chats for the latest 2 months but it is not very useful without something that can spoil your reputation... I recorded your masturbation and the video that you watched. It was disgusting. I can destroy your life by sending this stuff to everybody you know. If you want me to delete this stuff and avoid any problems you have to send $1000 to my bitcoin address: 1FDVdXo5f7bCdiw6AijyQU2Hc9XcZ17Gia If you don't know how to buy bitcoins use Google, there are a lot of manuals about using, spending and buying this cryptocurrency. You have 50 hours from now to complete the payment. I have a notification that you are reading this message... TIME HAS GONE. Don't try to respond because this email address is generated. Don't try to complain because this and my bitcoin address can't be tracked down. If I notice that you shared this message everybody will receive your data. Bye!

PHISHING LINKs;

1. support@algotrack.in 

How to tell this is a Phishing email ?

1. Check email address in full, if it's not from originating company then it's phishing.
2. Hover over all links in email, if it's not from the  company's website then forget it.
3. The best way is to 

How to examine Email Message Source ?

Now lets look at message source

1. Outlook.com->Actions->View Message Source. 
2. Gmail.com->More (down arrow to top right)->Show original.

Check for suspicious links, anything that does not originate from apple.com.

Report Phishing Email (not as Spam)

1. Outlook.com->Junk (at Top)->Phishing Scam
2. Gmail.com->More (down-arrow to top right)->Report Phishing 

Report Phishing

If you have recievied this email take further 

1. https://www.google.com/safebrowsing/report_phish/

Report phishing at Microsoft and government agencies

1. http://www.microsoft.com/security/online-privacy/phishing-faq.aspx

Amazon Phishing Email - FWD: Important: [New-Noticed] : Your Account - Blocking Logged 25/10/2020 Available

For the record, this is an Amazon phishing email attempt that is recently going around, with subject "FWD: Important: [New-Noticed] : Your Account - Blocking Logged 25/10/2020 Available" What to do?  Report them, goto bottom of page. 

From : Amazon.com <5to4xxxx-xxxxxxx@bujanglapet.com>  Subject : FWD: Important: [New-Noticed] : Your Account - Blocking Logged 25/10/2020 Available Text for search engines  --------------------------- Yo͏u͏r Ama͏z͏o͏n Ac͏c͏o͏u͏n͏t͏ a͏re on ho͏l͏d͏ due to a bil͏l͏i͏n͏g issue Update Payment Information Due to a problem with your card, we have been unable to charge your payment. If you don't update your card information in the next 24 hours, your Amazon account are on hold permanently. To continue using your account, please visit this link to log in to your account and update your payment information. Thank you, Amazon.com Customer Service

PHISHING LINKs;

1. http://go.mollyiss.com/?COPGWAPMZL 

How to tell this is a Phishing email ?

1. Check email address in full, if it's not from originating company then it's phishing.
2. Hover over all links in email, if it's not from the  company's website then forget it.
3. The best way is to 

How to examine Email Message Source ?

Now lets look at message source

1. Outlook.com->Actions->View Message Source. 
2. Gmail.com->More (down arrow to top right)->Show original.

Check for suspicious links, anything that does not originate from apple.com.

Report Phishing Email (not as Spam)

1. Outlook.com->Junk (at Top)->Phishing Scam
2. Gmail.com->More (down-arrow to top right)->Report Phishing 

Report Phishing

If you have recievied this email take further 

1. https://www.google.com/safebrowsing/report_phish/

Report phishing at Microsoft and government agencies

1. http://www.microsoft.com/security/online-privacy/phishing-faq.aspx