The name 'sr' doesn't exist in current context

Question

I was following example from microsoft site for reading from text file. They say to do it like this:

class Test
{
    public static void Main()
    {
        try         


        

Answer 1

What you described is achieved by putting ; after using statement

using (StreamReader sr = new StreamReader("TestFile.txt"));
{
     String line = sr.ReadToEnd();
     Console.WriteLine(line);
}

Possibly you even didn't notice that and deleted later.

What's the difference between using(StreamReader) and just StreamReader?

When you put disposable variable (StreamReader) in using statement it's the same as:

StreamReader sr = new StreamReader("TestFile.txt");
try
{
    String line = sr.ReadToEnd();
    Console.WriteLine(line);
}
finally
{
    // this block will be called even if exception occurs
    if (sr != null)
        sr.Dispose(); // same as sr.Close();
}

Also if you declare variable in using block, it will be visible only in using block. Thats why ; made your StreamReader non-existing in latter context. If you declare sr before using block, it will be visible later, but stream will be closed.