C#

public partial class mainfrm : Form
{

    public mainfrm()
    {
        InitializeComponent();
    }

    private void rfButton_Click(object sender, EventArgs e)
    {
        OpenFileDialog open = new OpenFileDialog();

        open.Title = "Select A Text File";
        open.InitialDirectory = @"C:\";
        open.Filter = "Supported Files|*.txt";
        open.Multiselect = false;
        open.ReadOnlyChecked = false;

        if (open.ShowDialog() == DialogResult.OK)
        {
            foreach (string filename in open.FileNames)
            {
                textRead.ReadText(open.FileName);
            }
        }
    }
    private void ProcessText(string text)
    {
        textBox1.Text = text;
        textBox1.Invalidate();
    }
 }

public class textRead
{
    public delegate void AddText(string text);
    public AddText TextSender
    {
        get
        {
            return TextSender;
        }
        set
        {
            TextSender = value;
        }
    }

    public static void ReadText(string source)
    {
        using (StreamReader sr = new StreamReader(source))
        {
            this.TextSender(sr.ReadLine());
            //^Keyword 'this' is not valid in a static property, static method, or static field initializer
        }
    }
}

Alexander Wiseman wrote:

That being said, my original confusion remains, because it seems like, from the MSDN documentation, there is nothing required on the part of the user of the System.String class to ensure thread safety. What little I have read concerning "immutability" of the string type would support this. On the other hand, if I am doing multiple write operations and multiple read operations, is there going to be a problem?

Alexander Wiseman wrote:

Let me just make sure I have this clear with a quick example. Let us say that I have two threads, A and B, both of which have access to String someStr = "My String".

Now let's say that the processor gives a time-slice to thread A, which then reads the string. Then the processor gives a time-slice to thread B, which then changes the string from "My String" to "Your String".

If I understand you correctly, then because strings are immutable, no matter when the processor decides to temporarily stop processing on thread A, nevertheless thread A will still see the value "My String", even though thread B may have "changed" it already. Is that correct?

string someString = "My String";

someString = "Your String";

string someString = "My String";

// Just making this method up for the example.
someString.Concatenate(" and Your String");

// Output: "My String and Your String"
Console.WriteLine(someString);

string someString = "My String";

string anotherString = someString.Concatenate(" and Your String");

// Output: My String"
Console.WriteLine(someString);
// Output: My String and Your String"
Console.WriteLine(anotherString);