MemoryStream from string - confusion about Encoding to use

c# .net encoding

12,259

Assuming applicationForm is a string you read from some UTF8 text file. It will be UTF16/Unicode, whatever the encoding of the source file. The conversion happened when you loaded the file into the string.

Your code will encode the applicationForm string into a MemoryStream of UTF8 bytes.

This may or may not be correct depending on what you want to do with it.

.Net strings are always UTF16 or Unicode. When Strings are converted to files, streams or byte[], they can be encoded in different ways. 1 byte is not enough to store all the different characters used in all languages so more complicated strings need to be encoded so one character can be represented by more than one byte, Sometimes or always depending on the encoding used.

If you use a simple encoding like ASCII one character will always comprise of one byte but the data will be limited to the ASCII character set. Converting to 'ASCII' from any UTF encoding could lose data if any multi-byte characters are used.

For the complete picture on unicode go here.

EDIT 1: Barring further info on the GenerateApplicationForm component, enconding UTF8 is likely to be the right choice. If that doesn't work, try ASCII or UTF16. Best of all, consult the component source code or the component provider.

EDIT 2: Definitely UTF8 then, you were right all along.

12,259

Author by

loczek

Updated on June 16, 2022

Comments

loczek almost 2 years
I have a piece of code that converts string into memory stream:
```
using (MemoryStream stream = new MemoryStream(Encoding.UTF8.GetBytes(applicationForm)))
```
However I'm a bit confused if it's correct. Basically I'm always confused about .NET encoding.

Bottom line: do I use correct encoding object (UTF8) to get bytes?

I know that internally .NET stores string as UTF-16, but my applicationForm variable was based on file with text which was saved in UTF-8 encoding.

Thanks,Pawel

EDIT 1: Let's explain exactly how I get applicationForm variable. I do have access to assembly that exposes class with method GenerateApplicationForm. That method returns string. However I know, that somewhere behind the scenes, component uses files stored on drive.Content of those files are encoded using UTF-8. So I can't read file directly etc. I only have that string and I know, that originally, UTF-8 encoded file is used. In client code, the one that used GenerateApplicationForm component, I have to convert applicationForm variable into stream, cos other components (from another assembly) is expecting a Stream. That's where using.... statement mentioned in question springs into action.
- ibram almost 13 years
  
  If this works, don't touch it.
- ibram almost 13 years
  
  But it depends on the data you are working on.
- Steve B almost 13 years
  
  what are trying to achieve ? how is applicationForm populated ? it's a string... it is in utf-16 in memory, event if it has been loaded from a utf-8 file
- Jodrell almost 13 years
  
  What types of encoding does the GenerateApplicationForm component support in the passed stream? This is the crux of the question.
- loczek almost 13 years
  
  UTF-8. GenerateApplicationForm in fact is used in some kind of mediator. That mediator: a) receives string (from component X - which in fact is GenerateApplicationForm - that generates application forms) b) changes string into stream c) passes stream to component Y. Component Y expects stream of encoding UTF-8.
loczek almost 13 years

I've added some info to question. Please check if your answer is still relevant.
loczek almost 13 years

Basically I don't open the data. Please check my EDIT in question.
loczek almost 13 years

I've added some details to question. Perhaps it'll help the issue I'm dealing with. Thanks
Jodrell almost 13 years

What types of encoding does the GenerateApplicationForm component support in the passed stream? This is the crux of the question.
loczek almost 13 years

UTF-8. GenerateApplicationForm in fact is used in some kind of mediator. That mediator: a) receives string (from component X - which in fact is GenerateApplicationForm - that generates application forms) b) changes string into stream c) passes stream to component Y. Component Y expects stream of encoding UTF-8.
loczek almost 13 years

Ok, I think I'm starting to get it. So decisive conclusion is: Encoding.UTF8.GetBytes(applicationForm)) line makes on-the-fly conversion of UTF-16 string representation in .NET into UTF-8?
blowdart almost 13 years

It doesn't make an on-the-fly comparison - see my answer. It's taking a textual representation of a binary value, and turning it back into binary. This has nothing to do with how .NET treats strings internally.
Jodrell almost 13 years

@dragonfly, I agree with blowdart. It doesn't matter what is inside string (just happens to be UTF16.) What matters is when you turn the string back into bytes, what bytes will be made to represent the text i.e. what encoding will be used.