1. File Input/Output (I/O)
Tonga Institute of Higher Education

2. Working with Files and Directories
Programs often work with files
Changing files or directories
Getting information about file or directory
Getting data form a file or directory
Saving data in a file or directory

3. System.IO Namespace
The System.IO namespace contains many classes we can use to work with files and directories
DirectoryInfo
FileInfo
StreamReader
StreamWriter

4. Demonstration
FileInfo

5. What is a Stream? Stream A stream is a sequence of data
Streams are used to move data from one place to another
In our computer:
You can read from streams. Reading is the transfer of data from a stream into a data structure, such as a variable.
You can write to streams. Writing is the transfer of data from a data structure, such as a variable, into a stream.
Data Source
Destination
Stream

6. Writing and Reading Streams
StreamReader – Object allows program to read data from a file using a stream.
StreamWriter – Object allows program to write data to a file using a stream.

7. StreamReader Allows a program to read characters from a file
Name of the file
that will be read
Loads 1 line
Always close the file. Close releases any resources used by the system

8. StreamReader 2
The end of the file is reached
when line is nothing

9. Demonstration
StreamReader

10. StreamWriter Allows a program to write characters to a file
Name of the file
that will be written
WriteLine includes
a carriage return
Close releases any resources
used by the system

11. Demonstration
StreamWriter

12. File Dialog Boxes
Often, a user needs a GUI to select a file to open or enter the name and location of a file to save
OpenDialogBox - Provides GUI for selecting a file to open
SaveDialogBox - Provides GUI for inputting the name and location of a file to save

13. Open Dialog Box
Provides GUI for selecting a file to open

14. Open Dialog Box GUI The properties can be set using the GUI
There are many
properties
The properties can be set using the GUI

15. Open Dialog Box GUI Code
But code must be used to display it and handle what the user does with it.

16. OpenFileDialog with GUI and Code
Demonstration
OpenFileDialog with GUI and Code

17. Using OpenFileDialog with Only Code
Many developers prefer to create source code when using the OpenFileDialog box
This allows the developer to see everything they have done

18. OpenFileDialog with Only Code
Demonstration
OpenFileDialog with Only Code