some File I/O fun

Say we say I have "Hello" in C:\MyFile.txt and we want add the "World" after the hello. To accomodate, I used to read everything from the file to a string, add to the string, and then write the string back to a text file like so:

using (Stream textReaderAndWriter = new FileStream(@"C:\MyFile.txt", FileMode.Open))
{
   byte[] dataCapacity = new byte[0x100];
   textReaderAndWriter.Read(dataCapacity, 0, dataCapacity.Length);
   string concatinationGrounds = "";
   foreach(char character in ASCIIEncoding.ASCII.GetString(dataCapacity))
   {
      if (char.IsLetterOrDigit(character))
      {
         concatinationGrounds += character;
      }
   }
   concatinationGrounds = concatinationGrounds + " World";
   textReaderAndWriter.Position = 0;
   dataCapacity = ASCIIEncoding.ASCII.GetBytes(concatinationGrounds);
   textReaderAndWriter.Write(dataCapacity, 0, dataCapacity.Length);
}

 
 

Today, I finished reading Chapter 14 of C# 4.0 in a Nutshell which is on File I/O (input/output) stuff. I thought that one of the things I learned in this chapter was this appending shortcut...

byte[] extraData = ASCIIEncoding.ASCII.GetBytes(" World");
using (Stream textAppender = new FileStream(@"C:\MyFile.txt", FileMode.Append))
{
   textAppender.Write(extraData, 0, extraData.Length);
}

 
 

...but then I dug up some of my old notes and found I had done this before:

 
 

So what did I learn from this chapter?

1. Flush() per the book: "forces any internally buffered data to be written immediately"
2. \r is a "carriage return" and \n is a "line feed" so think of \r\n as a ReturN
3. fileInfo.Attribures ^= FileAttributes.Hidden; will toggle the hidden flag from true to false or false to true for a FileInfo object
4. CRC is cyclic redundancy check
5. UAC stands for User Account Control and this is the Windows feature that asks you: "Do you want to allow the following program to make changes to this computer?"
6. In new byte[0x100] the 0x notation is hexadecimal in which:
   • 0x10 is 16
   • 0x100 is 16 x 16 or 256
   • 0x1000 is 16 x 16 x 16 which is some big number
   • etc.