FILE I/O Operations

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FILE I/O Operations
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Writing to a file

• In C language System.IO namespace is used for
  file operations.
• We should use StreamWriter class especially when
  Turkish support is needed.
• Turkish language support is provided by Encoding
  class in System.Text namespace.

Needed namespaces
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Writing to a file

• StreamWriter Used for writing to a file.
• Encoding Used for determining character code
  page of the file.
• StreamWriter.WriteLine(string) Writes a line to
  the file.

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Writing to a file
File name and path
Object that will write to the file
Crates file with Turkish support
Write a line to the file
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Exercise

• Write a program that inserts the lines that are
  taken from console to a file. Program will stop
  if user enters wq!

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Formatting Strings

• string.Format used for formatting strings with a
  given format.
• We could be asked for writing our files in a row
  and column basis. We could use string.Format
  function at these situations.

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Formatted Writing
In the example above, lines are written to the
file with right alignment. Because we used
string.Format function before writing to the
console. First parameter of the function tells
to reserve 20 characters of space to the second
parameter.
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Exercise

• Write a program that writes formatted data to a
  file which are taken from user.
• Program will first ask for student number then
  name and surname.
• Program will write these data to a file with
  reserved spaces for student number 15
  characters, name-surname 40 characters.
• Program will terminate after taking 5 student
  entry.

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Reading from file

• StreamReader Used for reading from a file.
• string StreamReader.ReadLine() Used from
  reading a line from a file.
• It is a good practice to check the existence of
  the file with File.Exists(string path) method
  before accessing the file.

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Reading from file
Open file for reading and create reader object.
Does file exist?
Read one line per iteration until end of file
Print the line that is read to the output
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Exercise

• Write a program that reads the student
  information from file which is created in the
  previous example.
• Program will read the file line by line and write
  each line to a new file. Each file will be named
  with the student name which it contains.
• In other words, after program is executed there
  will be 5 files for 5 students.

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Serialization

• It is used for storing and reading objects
  to/from a file which are not string types.
• We use FileStream and BinaryFormatter classes.
• System.IO. FileStream
• System.Runtime.Serialization.Formatters.Binary.
  BinaryFormatter
• Serialize and Deserialize functions are used for
  saving and loading.

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Serialization

• Serializable
• Marks whether class is serializable or not.

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Serialization - Serialize
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Serialization - Deserialize