I use a webservice that returns a zip file, as a string, and not bytes as I expected. I tried to write it to the disk, but when I open it, it tells me that it is corrupt. What am I doing wrong?
string cCsv = oResponse.fileCSV;//this is the result from webservice
MemoryStream ms = new MemoryStream(System.Text.Encoding.ASCII.GetBytes(cCsv));
using (FileStream file = new FileStream("test.zip", FileMode.Create, FileAccess.Write))
{
ms.WriteTo(file);
}
ms.Close();
I'm not sure what kind of encoding the string is in, but assuming UTF-8, the following should work. UTF-16 would be another guess.
string cCsv = oResponse.fileCSV;
using (BinaryWriter bw = new BinaryWriter(File.Create("test.zip")))
{
bw.Write(System.Text.Encoding.UTF8.GetBytes(cCsv));
}
It'd be informative to look at the characters and the raw string itself being returned.
Edit
Per Frank's answer, the correct encoding is base64, which of course makes sense because it's binary data stored as a string.
Also, per Frank's answer, if the only action is to directly write a single byte array, then File.WriteAllBytes is more compact.
Ok, i solve the problem:
File.WriteAllBytes("testbase64.zip", Convert.FromBase64String(cCsv));
Related
I have some product data that I want to write into a csv file. First I have a function that writes the header into the csv file:
using(StreamWriter streamWriter = new StreamWriter(path))
{
string[] headerContent = {"banana","apple","orange"};
string header = string.Join(",", headerContent);
streamWriter.WriteLine(header);
}
Another function goes over the products and writes their data into the csv file:
using (StreamWriter streamWriter = new StreamWriter(new FileStream(path, FileMode.Open), Encoding.UTF8))
{
foreach (var product in products)
{
await streamWriter.WriteLineAsync(product.ToString());
}
}
When writing the products into the csv file and do it with FileMode.Open and Encoding.UTF8, the encoding is set correctly into the file meaning that special characters in german or french get shown correctly. But the problem here is that I overwrite my header when I do it like this.
The solution I tried was to not use FileMode.Open but to use FileMode.Append which works, but then for some reason the encoding just gets ignored.
What could I do to append the data while maintaing the encoding? And also why is this happening in the first place?
EDIT:
Example with FileMode.Open:
Fußpflegecreme
Example with FileMode.Append:
Fußpflegecreme
The important question here is: what does the file actually contain; for example, if I use the following:
using System.Text;
string path = "my.txt";
using (StreamWriter streamWriter = new StreamWriter(new FileStream(path, FileMode.Create), Encoding.UTF8))
{
streamWriter.WriteLine("Fußpflegecreme 1");
}
using (StreamWriter streamWriter = new StreamWriter(new FileStream(path, FileMode.Append), Encoding.UTF8))
{
streamWriter.WriteLine("Fußpflegecreme 2");
}
// this next line is lazy and inefficient; only good for quick tests
Console.WriteLine(BitConverter.ToString(File.ReadAllBytes(path)));
then the output is (re-formatted a little):
EF-BB-BF-
46-75-C3-9F-70-66-6C-65-67-65-63-72-65-6D-65-20-31-0D-0A-
46-75-C3-9F-70-66-6C-65-67-65-63-72-65-6D-65-20-32-0D-0A
The first line (note: there aren't any "lines" in the original hex) is the UTF-8 BOM; the second and third lines are the correctly UTF-8 encoded payloads. It would help if you could show the exact bytes that get written in your case. I wonder if the real problem here is that in your version, there is no BOM, but the rest of the data is correct. Some tools, in the absence of a BOM, will choose the wrong encoding. But also, some tools: in the presence of a BOM: will incorrectly show some garbage at the start of the file (and may also, because they're clearly not using the BOM: use the wrong encoding). The preferred option is: specify the encoding explicitly when reading the file, and use a tool that can handle the presence of absence of a BOM.
Whether or not to include a BOM (especially in the case of UTF-8) is a complex question, and there are pros/cons of each - and there are tools that will work better, or worse, with each. A lot of UTF-8 text files do not include a BOM, but: there is no universal answer. The actual content is still correctly UTF-8 encoded whether or not there is a BOM - but how that is interpreted (in either case) is up to the specific tool that you're using to read the data (and how that tool is configured).
I think this will be solved once you explicitly choose the utf8 encoding when writing the header. This will prefix the file with a BOM.
I download the SevenZipSharp Lib in order to compress some files.
I used this in order to compress a file :
var libPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles), "7-zip", "7z.dll");
SevenZip.SevenZipCompressor.SetLibraryPath(libPath);
SevenZip.SevenZipCompressor compressor = new SevenZipCompressor();
compressor.CompressFiles(#"C:\myTestFile.mdf", new string[] { #"C:\myTestFileCompressed.7z" });
With this, my file is compressed whitout problem. I can decompressed it.
Now...i would like to compress the same file, but, instead of compress directly the file, i would like to :
Read the file in a string. Yes, in a string, and not in a byte[].
Convert my string to byte[]
Compress the byte[] to another byte[].
Here is my try :
string strToCompress = File.ReadAllText(#"C:\myTestFile.mdf");
SevenZipCompressor compressor = new SevenZipCompressor();
byte[] byteArrayToCompress = Encoding.ASCII.GetBytes(text);
MemoryStream stream = new MemoryStream(byteArrayToCompress);
MemoryStream streamOut = new MemoryStream();
compressor.CompressStream(stream, streamOut);
string strcompressed = Encoding.ASCII.GetString(streamOut.ToArray());
File.WriteAllText(#"C:\myfileCompressed.7z",strcompressed);
My problem is very simple :
If i compare the size produced by these 2 methods, it's 3 603 443 bytes vs 3 604 081 bytes.
In addition, i cannot uncompressed the file produced by the second method.
Maybe it's because i used ASCII encoding, but my file to compress is not a Text, it's a binary file.
Anyone could explain me how solving it please ? I need to read my file to a string and compress it. ( i don't want to read the file directly to a byte[]).
Thanks a lot,
Best regards,
Nixeus
You cannot put binary data into a string, not every byte value has a Unicode codepoint. Using ASCII encoding will similarly always cause irretrievable data loss, it only has characters for byte values 0 through 127, higher values will produce a ?
You certainly can convert a byte[] to a string, it needs to be encoded. The standard encoding that's used for that is available in .NET from the Convert.ToBase64String() method. You recover the byte[] again with Convert.FromBase64String(). Inevitably it won't be as compact, it will be 4/3 bigger as the original data in a byte[].
You can never produce a valid .7z archive that way, it of course uses the most compact possible storage and that is bytes. You must pass a FileStream to the CompressStream() method.
I am trying to write integer numbers to binary file, but it keeps giving weird characters in the binary file. For example, I try to write 2000, but in the file i will get something strange. How do I fix it? Couldn't find the solution anywhere.
I use the following code:
//create the file
FileStream fs = new FileStream("iram.bin", FileMode.Create);
// Create the writer for data.
BinaryWriter w = new BinaryWriter(fs);
w.Write((int) 2000);
w.Close();
fs.Close();
I think the problem is that you are not reading the data back properly.
You will need to read the data back using a BinaryReader like so...
using (FileStream fs2 = new FileStream("iram.bin", FileMode.Open))
{
using(BinaryReader r = new BinaryReader(fs2))
{
var integerValue = r.ReadInt32();
}
}
Unless of course you actually want to write text to the file in which case you probably don't want a BinaryWriter to write the data out.
If you actually want to write out text data you could do so like this... (Be sure to set your encoding to what you need)
using (var tw = new StreamWriter("iram.txt", true, Encoding.ASCII))
{
tw.WriteLine(2000);
}
Edit: As Jesse mentioned you normally want to wrap disposable objects in using blocks.
The reason you're getting unexpected chars in the file is because what you're writing to the file is not meant to be interpreted as a sequence of chars in the first place
When you open it in notepad or another text editor, It will just take what's there, guess the encoding(or use a default), and show you whatever chars the data would encode if it were encoding chars. It's not intended to be human readable.
A human readable text file that has the character sequence 2000 actually has an encoding of the character 2, followed by the encoding of 0 3 times.
in Unicode it's U+0032U+0030U+0030U+0030
What is the best way to save a file to my SQL database using Silverlight and LINQ?
I have read through some articles, some of them here on StackOverflow and there is so much information that I am not sure what is the best.
I have something that works using:
// Read the file
var reader = new StreamReader(openFileDialog.File.OpenRead());
contents = reader.ReadToEnd();
reader.Close();
// Convert to byte[]
byte[] inputbuffer;
var encoding = new UTF8Encoding();
inputBuffer = encoding.GetBytes(contents);
but according to something I read here on StackOverflow, using UTF8Encoding is not a good idea.
Also I can get the file from the database using LINQ when I need it, but how do I convert it back from the byte[] to the actual file?
Or would using WCF to save and retrieve a file be better?
Any ideas are greatly appreciated.
yes UTF8Encoding is not a good option.
You can use the FileStream's copyto method to copy the files bytes into a memorystream and use it's ToArray method to get all bytes instead.
If you can access the DB directly from Silverlight than this should be ok but the second part of your questions indicates that you might not be sure(?) - if so please put this into another question.
Here is a snippet to return the bytes from the file:
var stream = openFileDialog.File.OpenRead();
using (var memStream = new System.IO.MemoryStream())
{
stream.CopyTo(memStream);
return memStream.ToArray();
}
To save it back you will have to use the SaveFileDialog class in silverlight
I have a byte array for a file, is there a way to take that and save it has a file to a remote file server?
File.WriteAllBytes(#"\\server\public_share\MyFile.txt", byteArray);
Writing your data to file is the simple part and #aaron has shown you how...
i.e. File.WriteAllBytes(....etc
But something to be aware of, if you're transferring binary data over the wire and if your data contains bytes that could be interpreted as control characters then your data transfer will be problematic.
What you may need to do is encode your data first so that you can transfer it safely, typically you would use something like Base64 encoding.
You can use the Convert helper class to do that...
Convert.ToBase64String("file contents");
If you are doing this in the codebehind then you will need to use the FileStream and BinaryWriter objects.
Something like this;
FileStream filestream = new FileStream("myfile.txt", FileMode.Open);
BinaryReader br = new BinaryReader(filestream);
String msg = br.ReadString();
br.Close();
filestream.Close();
FileStream networkStream = new FileStream(#"\\server\share\file.txt", FileMode.Create);
BinaryWriter bw = new BinaryWriter(filestream);
bw.Write(msg);
bw.Close();
networkStream.Close();
If you're passing it through Javascript maybe using a HTML browse button then you'll need to do the same sort of thing but you will get the file stream from the post form request.
You may have an issue writing to the network location, if you're using IIS then you could set up a virtual directory and set the credentials in IIS. The alternative is that you will need to do impersonation to write the file to the network server.
Mike