how to load a file into memory stream

I have a filename pointing to a text file, including its path, as a string. Now I'd like to load this .csv file into memory stream. How should I do that?

For example, I h开发者_如何学编程ave this:

Dim filename as string="C:\Users\Desktop\abc.csv"

Dim stream As New MemoryStream(File.ReadAllBytes(filename))

You don't need to load a file into a MemoryStream.

You can simply call File.OpenRead to get a FileStream containing the file.

If you really want the file to be in a MemoryStream, you can call CopyTo to copy the FileStream to a MemoryStream.

I had an XML file being read from disk, using the old XmlReader API. How to read the XML file into memory, and then work with it in memory, instead of reading the disk repeatedly? Based on VB answer from Centro (upvoted) but with a Using block, and in C#.

The key line:

MemoryStream myXMLDocument = new MemoryStream(File.ReadAllBytes(@"c:\temp\myDemoXMLDocument.xml"));

Re the OP's question, if you wanted to load a CSV file into a MemoryStream:

MemoryStream myCSVDataInMemory = new MemoryStream(File.ReadAllBytes(@"C:\Users\Desktop\abc.csv"));

Following is a code snippet showing code to reads through XML document now that it's in a MemoryStream. Basically the same code as when it was coming from a FileStream that pointed to a file on disk. Yes, the XMLTextReader API is old and clunky, but it's what I had to work with in this app.

    string myXMLFileName = @"c:\temp\myDemoXMLDocument.xml";
    using (MemoryStream myXMLDocument = new MemoryStream(File.ReadAllBytes(myXMLFileName)))
    {
            myXMLTextReader = new XmlTextReader(myXMLDocument);
            myXMLTextReader.WhitespaceHandling = WhitespaceHandling.None;
            myXmlTextReader.Read(); // read the XML declaration node, advance to <Batch> tag
            while (!myXmlTextReader.EOF) 
            {
                if (myXmlTextReader.Name == "xml" && !myXmlTextReader.IsStartElement()) break;
                // advance to <Batch> tag
                while (myXmlTextReader.Name == "Batch" && myXmlTextReader.IsStartElement())
                {
                    string BatchIdentifier = myXmlTextReader.GetAttribute("BatchIdentifier");
                    myXmlTextReader.Read(); // advance to next tag
                    while (!myXmlTextReader.EOF)
                    {
                        if (myXmlTextReader.Name == "Transaction" && myXmlTextReader.IsStartElement())
                        {
                            // Start a new set of items
                            string transactionID = myXmlTextReader.GetAttribute("ID");
                        myXmlTextReader.Read(); // Read next element, possibly another Transaction tag
                    }
                }
                //All Batch tags are completed.Move to next tag
                myXmlTextReader.Read();
            }
            // Close the XML memory stream.
            myXmlTextReader.Close();
            myXmlDocument.Close();
        }
    }

You can copy it to a file stream like so:

string fullPath = Path.Combine(filePath, fileName);
FileStream fileStream = new FileStream(fullPath, FileMode.Open);
Image image = Image.FromStream(fileStream);
MemoryStream memoryStream = new MemoryStream();
image.Save(memoryStream, ImageFormat.Jpeg);
//Close File Stream
fileStream.Close();