1. Application on File Program
Session 8

2. Objectives
 Typically example of file read & write
 Simple File Handling Program
 Several Home work

3. Typical example of file read & write
try
{
FileStream aFile = new FileStream("Log.txt",
FileMode.OpenOrCreate);
StreamWriter sw = new StreamWriter(aFile);
bool truth = true // Write data to file.
sw.WriteLine("Hello to you.");
sw.WriteLine("It is now {0} and things are looking
good.“,DateTime.Now.ToLongDateString());

4. sw.Write("More than that,");
sw.Write(" it’s {0} that C# is fun.", truth);
sw.Close();
}
catch (IOException ee)
{
Console.WriteLine("An IO exception has been
thrown!");
Console.WriteLine(ee.ToString());
Console.ReadLine();
return;
}

5. • Go to the application directory and find the Log.txt
file. It is located in the binDebug folder because you
used a relative path.
• The WriteLine() method writes the string passed to
it, followed immediately by a newline character.
• You can see in the example that this causes the next
write operation to begin on a new line.
• The Write() method simply writes the string passed
to it to the file, without a newline character appended.
• Two sentence is in one line.

6. The StreamReader Object
• try
• {
• FileStream aFile = new FileStream("Log.txt", FileMode.Open);
• StreamReader sr = new StreamReader(aFile);
• line = sr.ReadLine();
• // Read data in line by line.
• while(line != null)
• {
• Console.WriteLine(line);
• line = sr.ReadLine();
• }
• sr.Close();
• }

7. • catch(IOException e)
• {
• Console.WriteLine("An IO exception has been thrown!");
• Console.WriteLine(e.ToString());
• return;
• }
• Console.ReadKey();
 ReadLine() method to read text from the file.
 This method reads text until a new line is found,and returns
the resulting text as a string.
 The method returns a null when the end of the file has been
reached, which you use to test for the end of the file.

8.  Note that you use a while loop, which ensures that the line
read isn’t null before any code in the body of the loop is
executed.
Simple File Handling Program
String line,k="";
StreamReader sr = new
StreamReader("E:trainingreadsample.txt");
StreamWriter sw = new
StreamWriter("E:trainingWritesample.txt");
line = sr.ReadLine();

9. while (line != null)
{
k += line;
line = sr.ReadLine();
}
sw.WriteLine(k);
sw.Close();
sr.Dispose();
Direct using streamReader & streamWriter

10. Input :
readsample.txt Contain
• welcome TO .NET WORLD.
• Asp.Net IS Microsoft Own Product.
• File handling is done by Streamreader & streamwriter
• Simple program about File.
• OutPut:
• Writesample.txt Contain
• welcome TO .NET WORLD.Asp.Net IS Microsoft
Own Product.File handling is done by Streamreader
& streamwriter .Simple program about File.

11. Tasks(to be done in the class session):
• 1)Print first 5 characters from a file in a single line.
• 2)Print number of each line.
• 3)Create two files where 1st
file will contain 1st
&3rd
lines and the other file will contain 2nd
&4th
lines.