Re: Converting a unicode value (with a surrogate pair) to a character in C# - C# Discussion Boards

Re: Converting a unicode value (with a surrogate pair) to a character in C#

31-Dec-10 4:03

Hi Guys,

I want to know how to get the correct character from a unicode value which has a surrogate key. For example:

Here is my code that works with most characters:

public static char ConvertUnicodeToCharacter(string unicodeValue)
{
int unicode = int.Parse(unicodeValue.Substring(2), NumberStyles.HexNumber);
return (char)unicode;
}

This will take in something (like U+3400 for example) and spit out the character (in this case: 㐀).

When I try this one: U+2A601, I always get this: ꘁ, but it should be this: 𪘁.

Info on surrogate pairs:

"UTF-16 Encoding Form. The Unicode encoding form that assigns each Unicode scalar value in the ranges U+0000..U+D7FF and U+E000..U+FFFF to a single unsigned 16-bit code unit with the same numeric value as the Unicode scalar value, and that assigns each Unicode scalar value in the range U+10000..U+10FFFF to a surrogate pair" - http://www.unicode.org/glossary/

I just want to convert U+2A601 to 𪘁. Anyone know how?

Thanks

Richard MacCutchan31-Dec-10 4:53

Re: Converting a unicode value (with a surrogate pair) to a character in C#

31-Dec-10 4:53

gordon_matt wrote:
I just want to convert U+2A601 to 𪘁. Anyone know how?

This is 20-bits and therefore not a Unicode character; are you sure this value is correct?

Just say 'NO' to evaluated arguments for diadic functions! Ash

vnmatt31-Dec-10 5:06

Re: Converting a unicode value (with a surrogate pair) to a character in C#

31-Dec-10 5:06

Here you can see the character:
http://www.cojak.org/index.php?function=code_lookup&term=2A601[^]

I'm not sure what you're on about with the 20-bits thing, but if you have a way for me to turn U+2A601 into that character in c#, that would be great. That's all I am after. Smile | :)

Richard MacCutchan31-Dec-10 5:58

Re: Converting a unicode value (with a surrogate pair) to a character in C#

31-Dec-10 5:58

gordon_matt wrote:
I'm not sure what you're on about with the 20-bits thing

Hex value 2A601 is five digits which is 20-bits, Unicode characters are only 16 bits. I'm not sure what translation table is being used in the link you posted, but I would suggest an email to the person who made the website as the best step forward.

Just say 'NO' to evaluated arguments for diadic functions! Ash

jschell31-Dec-10 7:43

Re: Converting a unicode value (with a surrogate pair) to a character in C#

31-Dec-10 7:43

Richard MacCutchan wrote:
Hex value 2A601 is five digits which is 20-bits, Unicode characters are only 16 bits

In what context?

Unicode as a standard supports any number of character sets. Bits has nothing to do with that.

Each set is demarked by a minimum representational size called a code point which can be 8 bits, 16 bits, 32 bits and even 64 bits.

The full range of characters in each set (which is not necessarily all possible unicode characters) is represented by one or more code points.

The OP is asking about surrogate pairs in a 16 bit set. A suitable description of that is found here. One can find it at unicode.org as well but is requires digging.

http://en.wikipedia.org/wiki/UTF-16/UCS-2[^]

And C# certainly supports surrogate pairs. The following references the upper limit of 10FFFF which would be 21 bits. And 2A601 is certainly in that range.

http://msdn.microsoft.com/en-us/library/aa664669(v=vs.71).aspx[^]

Perhaps you are stating that 2A601 is not a valid character in the character set?

Richard MacCutchan1-Jan-11 0:36

Re: Converting a unicode value (with a surrogate pair) to a character in C#

1-Jan-11 0:36

Very interesting, and I stand corrected. But what is the answer to the OP's question?

Just say 'NO' to evaluated arguments for diadic functions! Ash

jschell31-Dec-10 7:52

Re: Converting a unicode value (with a surrogate pair) to a character in C#

31-Dec-10 7:52

gordon_matt wrote:
I want to know how to get the correct character from a unicode value which has a surrogate key. For example:

The data type 'char' only has 16 bits.

For C# the full range of unicode characters extends to 10FFFF, which will not fit in a 'char'.

The char represents a code point not a character in the full range of unicode character set.

A surrogate pair is by definition two code points. So to represent it you must have two 'char' values.
Alternatives would be to use an 'int' or a String.

vnmatt31-Dec-10 17:39

Re: Converting a unicode value (with a surrogate pair) to a character in C#

31-Dec-10 17:39

Thanks for the reply. I understand this well enough, but maybe everyone here is not quite understanding what I want...

Okay don't return a System.Char... give me a System.String...whatever....

I just want to do something like this:

public string GetUnicodeCharacter(string uniValue)
{
//uniValue = "U+2A601"
//Do some logic
return myUnicodeCharacter; //string that will display 𪘁
}

It seems nobody knows how to get this and it is driving me nuts. Yes I did email the author of that site (cojak.org), but no reply yet; maybe because of holidays, but I'll be lucky if he helps me anyway (not to mention his site is PHP, so might not be able to help with .NET).

Maybe there is a way to get the surrogate values from the "U+2A601" string? Then I could do something (ugly as it may be) like this:

public string myImaginaryMethod()
{
   string original = "\u2A601";
   string highSurrogate = GetHighSurrogate(original); // returns "\uD869";
   string lowSurrogate = GetLowSurrogate(original); returns "\uDE01";
   return highSurrogate + lowSurrogate; //returns 𪘁
}

Surely someone must know how to get this value somehow...anyhow...I don't care how, so long as I can get 𪘁 from "U+2A601"; (or from "\u2A601" would be fine too)

Smile | :)

jschell1-Jan-11 10:04

Re: Converting a unicode value (with a surrogate pair) to a character in C#

1-Jan-11 10:04

gordon_matt wrote:
It seems nobody knows how to get this and it is driving me nuts

Mentioning the surrogate pair probably confused the issue. It certainly did for me.

The following code should be what you want (with appropriate bit manipulation.) If not then could you provide the unicode.org page reference for 2A601 (I couldn't find it.)

// 2A601
byte[] array = new byte[4];
int i=0;
array[i++] = (byte)0x0001; // Little endian
array[i++] = (byte)0x00A6;
array[i++] = (byte)0x0002;
array[i++] = (byte)0x0000;

String r = System.Text.Encoding.UTF32.GetString(array);

vnmatt1-Jan-11 18:23

Re: Converting a unicode value (with a surrogate pair) to a character in C#

1-Jan-11 18:23

Thanks jschell. What Richard mentioned about it being 20 bits got me thinking this must be a UTF-32 character and after a LOT of research, I finally got the answer I needed and the solution is actually quite simple once you know what to look for:

If you pass in "U+2A601" to this method of mine, you'll get the correct character returned. I think I may go ahead and post a tip/trick on this Smile | :)

Thanks to all for helping point me in the right direction.

public static string ConvertUnicodeToCharacter(string unicodeValue)
        {
            int unicode = int.Parse(unicodeValue.Substring(2), NumberStyles.HexNumber);

            if (unicodeValue.Length == 7) //UTF-32
            {
                return char.ConvertFromUtf32(unicode);
            }

            return ((char)unicode).ToString(); //UTF-16
        }

Cheers

Richard MacCutchan2-Jan-11 2:40

Re: Converting a unicode value (with a surrogate pair) to a character in C#

2-Jan-11 2:40

I just came across this article[^] which may also contain some useful information.

Just say 'NO' to evaluated arguments for diadic functions! Ash

jschell2-Jan-11 8:57

Re: Converting a unicode value (with a surrogate pair) to a character in C#

2-Jan-11 8:57

I suspect the following would also work.

int unicode = int.Parse(unicodeValue.Substring(2), NumberStyles.HexNumber);
return char.ConvertFromUtf32(unicode);

Liao Jichen24-Feb-11 13:37

Liao Jichen

24-Feb-11 13:37

You can parse the "U+XXXXX" string into a integer of unicode, which in your case should be unicode=0x0002A601. Then you can ensurrogate to have two integers hi and lo.

int unicode, hi, lo;
unicode=0x0002A601;
hi = (unicode - 0x10000) / 0x400 + 0xD800;
lo = (unicode - 0x10000) % 0x400 + 0xDC00;

string s = new String(new char[] { Convert.ToChar(hi), Convert.ToChar(lo) });

The string s is 𪘁.

BTW, dealing with unicode, you may want to use System.Globalization.StringInfo.GetTextElementEnumerator to get a TextElement, check MSDN for more details.

Exception Handling

satsumatable31-Dec-10 1:16

satsumatable

31-Dec-10 1:16

Hi,

I have C# application with WCF service though I have proper Try.. Catch block in my application very rare when my application crashes or something that sort it didn't get into Catch Block and simply pop-up .Net debug window. What is the best way to configure my application to handle all the run time exception? Is there any configuration need to be set at Web/Application configuration etc ?

Thanks

Hiren solanki31-Dec-10 1:28

Hiren solanki

31-Dec-10 1:28

satsumatable wrote:
when my application crashes or something that sort it didn't get into Catch Block and simply pop-up .Net debug window.

When you're debugging with VS environment then I think it will always notify you with pop-up block when error occurs though you've specified try..catch..

satsumatable wrote:
What is the best way to configure my application to handle all the run time exception?

It's handling Exception itself, for the need it invented.

satsumatable wrote:
Is there any configuration need to be set at Web/Application configuration etc ?

Nothing just use Try..Catch block and Log the error catched by exception handling. That's it.

Regards,
Hiren.

My Recent Article: - Way to know which control have raised a postback
My Recent Tip/Trick: - Building Hierarchy using Recursive CTE

satsumatable31-Dec-10 1:39

satsumatable

31-Dec-10 1:39

static void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e)
{
}

Will this resolve ?

Hiren solanki31-Dec-10 1:43

Hiren solanki

31-Dec-10 1:43

See THIS[^] article for more detailed information.

Regards,
Hiren.

My Recent Article: - Way to know which control have raised a postback
My Recent Tip/Trick: - Building Hierarchy using Recursive CTE

Rob Philpott31-Dec-10 3:22

Rob Philpott

31-Dec-10 3:22

Sounds like you've got first chance exception-handling switched on in Visual Studio. Visual studio normally breaks on an unhandled exception, but you can change a setting so it happens 'first chance' on all exceptions, so even though you've got an exception block (which will still work just fine if you hit F5) it will break there none-the-less.

Have a look in your Debug->Exceptions menu.

Regards,
Rob Philpott.

Pete O'Hanlon31-Dec-10 3:24

Pete O'Hanlon

31-Dec-10 3:24

satsumatable wrote:
What is the best way to configure my application to handle all the run time exception?

You can't catch all runtime exceptions. If your application causes a stack overflow, or you run out of memory, the application is terminated immediately without going to the exception handler.

I'm not a stalker, I just know things. Oh by the way, you're out of milk.

Forgive your enemies - it messes with their heads

My blog | My articles | MoXAML PowerToys | Onyx

jschell31-Dec-10 7:59

31-Dec-10 7:59

satsumatable wrote:
have C# application with WCF service though I have proper Try.. Catch block in my application very rare when my application crashes or something that sort it didn't get into Catch Block and simply pop-up .Net debug window

There are three cases that can cause that.
1. Exceptions that cannot be caught. There are three of those, out of memory, stack overflow and an odd ball one that I can't remember and probably has nothing to do with your problem.
2. Exceptions that exits a thread block excluding the specific thread specific ones like interrupt. Any such exception will cause an application exit. The way to prevent this is to insure that all threads have try/catch at the top level. This includes asynchronous methods. And that might be the cause of your problem.
3. Unmanaged code and/or net errors. The second of these would be outside your control. The first means that you are using unmanaged code so presumably you would be aware of that.

Also note that AppDomain.UnhandledException will NOT prevent an application exit. All it does is provide a place for you to log what the exception was.