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c#: How to convert a Unicode character to its ASCII equivalent

I know its a recurrent question here but no one of answers havent work for me.
From a system I'm receiving a Unicode text. Just an email + name from customers.
When I record these strings to my SQL DB the appears some chars appears with \u.
For example the emails are getting in the DB: name\u0040domain.com
How I transform the Unicode string in my c# program to ascii, so the DB gets name#domain.com.
Also that replace special chars to equivalent or to no one... For example "Hernán π" to "Hernan "
Thanks!

IMHO converting Unicode back to ASCII for some dubious storage or technical benefit isn't a good idea in the 21st century, especially since email is being changed to support Unicode in headers and bodies.
http://en.wikipedia.org/wiki/Unicode_and_e-mail
If the reason why you want to convert Hernán to Hernan is for searching, you should look at using an Accent Insensitive (AI) collation on your database, or coerce it to do so - see this SO post.
One thing you might need to double check however is that your strings aren't getting preencoded before storage in your database (assuming that your DB column is set to accept unicode - i.e. NVARCHAR etc), the character '#' should be stored as '#' (0040 in UTF 16) and not as '\u0040'.
EDIT:
The "\uNNNN" encoding in a string might originate from Java or Python.
You might be able to trace the email string data up your architecture to find the source of this encoding and change it to something more easy to decode in C# such as UTF-8.
How do I treat an ASCII string as unicode and unescape the escaped characters in it in python?

You can use Encoding.Convert for such operations. Read about this on MSDN

Convert Hebrew Letters into Equivalent Number

Other then hard coding this by hand I was wondering if there was a way that the.net framework would have this built in automaticaly, I know it can automatically convert hebrew dates into georgian dates but I need to convert hebrew numbers into georgian
IE א
= 1
ב
= 2
This goes into the hundreds. See here for more info.

Here is the approach that you should take:
Make Dictionary<char,int> that gives correspondence between each Hebrew letter and its numeric value
Parse the string one character at a time (best to do it right-to-left)
For each character, look up its value in the dictionary and add it to a running sum
Be sure to handle common scenarios for separating the hundreds-letters from the tens-letters (double-quotation mark) and separating the thousands-letters from the hundreds (single-quotation mark). For example, 5770 = ה'תש"ע.`. See the details in the link above for more on separations.
Edit: I just published a GitHub Repo that exposes functionality for converting Hebrew text to numbers, and numbers to their Hebrew letter equivalents.

How to show symbols like "Lambda" or "Mu" on labels in desktop application in c#.net

Please tell me how can i show symbols like "lambda" or Mu using c#.net in desktop application. what i think is we may do it using ASCII values and convert.toChar();.. if i am right that please give me link of page where i can get ASCII values of all such a scientific symbols.
Please give me link of any URL which contains list of such a ASCII numbers.

Open the Windows character map (charmap.exe), select a Unicode font (Arial should suffice) and copy the symbols into your source code or resources. It's just characters. Of course, you can also switch to Greek keyboard layout, so you can write the characters directly rather than going the charmap route.
Note that you need to use a Unicode font for the labels. You can use charmap to look up which font has Greek characters.

Please tell me how can i show symbols like "lambda" or Mu using c#.net in desktop application.
You don't have to do anything special. Just use whatever letters you want in either the IDE or in strings in the program. C# treats Greek letters the same as any other letters; they are not special.
what i think is we may do it using ASCII values and convert.toChar();
Hold on, I have a phone call. Oh, it's for you. It's 1968 calling, and they want their character set back. :-)
ASCII proper only has 95 printable characters, and Greek letters are not among them. ASCII was invented for teletypes back in the 1960's; we don't use it anymore. Characters in modern programming environments are represented using Unicode, which provides uniform support for tens of thousands of characters in dozens of alphabets.
if i am right then please give me link of page where i can get ASCII values of all such a scientific symbols.
You can get a list of all the Unicode characters at unicode.org. But like I said, you don't need to. You can just embed the character you want directly in the text. There's no need to resort to clumsy tricks like unicode escapes. (Unless, of course, you are planning on sending your source code to your coworkers using a 1970's era teletype machine.)

C# applications are all Unicode - so there should be no problem assigning Unicode strings to the controls' text, for example:
textBox1.Text = "this is a lambda symbol - λ";

Try this
char c = '\u03BB'; //03BC
System.Console.WriteLine(c.ToString());
does it work for you?

How do I find out if my string contains the "micro" Unicode character?

I have a Excel Spreadsheet with lab data which looks like this:
µg/L (ppb)
I want to test for the presence of the Greek letter "µ" and if found I need to do something special.
Normally, I would write something like this:
if ( cell.StartsWith(matchSequence) ) {
//.. <-- universal symbol for "magic" :)
}
I know there is an Encoding API in the Framework, but should I use it for just this one edge-case or just copy the Greek micro symbol from the character map?
How would I test for the presence of a this unicode character? The character map seems like a "cheap" fix that will bite me later (I work for a company which is multinational).
I want to do something that is maintainable and not just some crazy math-voodoo conversion that only works for this edge case.
I guess I'm asking for best practice advice here.
Thanks!

You need to work out the unicode character you're interested in, then you can represent it with in code with an escape sequence.
For example, µ is U+00B5, so you just need:
if (text.Contains("\u00b5"))
You can find out the Unicode value from charmap or from the Unicode code charts.

The Unicode code point for micro µ is U+00B5 and is different from the "Greek letter mu" µ, which is at U+03BC. So you can use "\u00b5" to find it, and possibly also look for "\u03bc" as well - they look the same, so whoever created the spreadsheet could have used the wrong one!

You can create a Char from the numeric equivelent shown to you in the Character Map (displays as U+0050 for 'P'). To do this simply check the contains:
string value;
if (value.Contains(Char.ConvertFromUtf32(0x0050)))
;

C# code files are usually encoded in utf8, since the language is using this encoding. All strings and strign literals in c# (and other .NET languages) are encoded in utf16. So you can safely copy the micro character from the character map.
You can also use its integer value as unicode literal like 0x1234.

C#: How do you go upon constructing a multi-lined string during design time?

How would I accomplish displaying a line as the one below in a console window by writing it into a variable during design time then just calling Console.WriteLine(sDescription) to display it?
Options:
-t Description of -t argument.
-b Description of -b argument.

If I understand your question right, what you need is the # sign in front of your string. This will make the compiler take in your string literally (including newlines etc)
In your case I would write the following:
String sDescription =
#"Options:
-t Description of -t argument.";
So far for your question (I hope), but I would suggest to just use several WriteLines.
The performance loss is next to nothing and it just is more adaptable.
You could work with a format string so you would go for this:
string formatString = "{0:10} {1}";
Console.WriteLine("Options:");
Console.WriteLine(formatString, "-t", "Description of -t argument.");
Console.WriteLine(formatString, "-b", "Description of -b argument.");
the formatstring makes sure your lines are formatted nicely without putting spaces manually and makes sure that if you ever want to make the format different you just need to do it in one place.

Console.Write("Options:\n\tSomething\t\tElse");
produces
Options:
Something Else
\n for next line, \t for tab, for more professional layouts try the field-width setting with format specifiers.
http://msdn.microsoft.com/en-us/library/txafckwd.aspx

If this is a /? screen, I tend to throw the text into a .txt file that I embed via a resx file. Then I just edit the txt file. This then gets exposed as a string property on the generated resx class.
If needed, I embed standard string.Format symbols into my txt for replacement.

Personally I'd normally just write three Console.WriteLine calls. I know that gives extra fluff, but it lines the text up appropriately and it guarantees that it'll use the right line terminator for whatever platform I'm running on. An alternative would be to use a verbatim string literal, but that will "fix" the line terminator at compile-time.

I know C# is mostly used on windows machines, but please, please, please try to write your code as platform neutral. Not all platforms have the same end of line character. To properly retrieve the end of line character for the currently executing platform you should use:
System.Environment.NewLine
Maybe I'm just anal because I am a former java programmer who ran apps on many platforms, but you never know what the platform of the future is.

The "best" answer depends on where the information you're displaying comes from.
If you want to hard code it, using an "#" string is very effective, though you'll find that getting it to display right plays merry hell with your code formatting.
For a more substantial piece of text (more than a couple of lines), embedding a text resources is good.
But, if you need to construct the string on the fly, say by looping over the commandline parameters supported by your application, then you should investigate both StringBuilder and Format Strings.
StringBuilder has methods like AppendFormat() that accept format strings, making it easy to build up lines of format.
Format Strings make it easy to combine multiple items together. Note that Format strings may be used to format things to a specific width.
To quote the MSDN page linked above:
Format Item Syntax
Each format item takes the following
form and consists of the following
components:
{index[,alignment][:formatString]}
The matching braces ("{" and "}") are
required.
Index Component
The mandatory index component, also
called a parameter specifier, is a
number starting from 0 that identifies
a corresponding item in the list of
objects ...
Alignment Component
The optional alignment component is a
signed integer indicating the
preferred formatted field width. If
the value of alignment is less than
the length of the formatted string,
alignment is ignored and the length of
the formatted string is used as the
field width. The formatted data in
the field is right-aligned if
alignment is positive and left-aligned
if alignment is negative. If padding
is necessary, white space is used. The
comma is required if alignment is
specified.
Format String Component
The optional formatString component is
a format string that is appropriate
for the type of object being formatted
...