The StreamReader class provides us with a couple of methods and a property as listed below:
Close: Closes the StreamReader object and the underlying stream, and releases any system resources associated with the reader.
Peek: Returns the next available character but does not consume it.
Read: Reads the next character or next set of characters from the input stream.
ReadLine: Reads a line of characters from the current stream and returns the data as a string.
ReadToEnd: Reads the stream from the current position to the end of the stream.
To read a text file, we need to open it using System.IO.File.OpenText method which returns a StreamReader object. Once we obtain the StreamReader object, just call the appropriate method to pull the data.
oSR = System.IO.File.OpenText(sFilename);
txtOutput.Text = oSR.ReadToEnd();
Dim oSR As System.IO.StreamReader
oSR = System.IO.File.OpenText(sFileName)
txtOutput.Text = oSR.ReadToEnd()
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Sample applications can be downloaded here: VB.net or C#