Import Text.txt in lisBox.1

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This below is the code to import the Text file in listbox1, and it works. I need the code that checks the content in listBox1...I mean excluding the lines that are already in the listbox1. Thank you.

C#

private void button1_Click(object sender, EventArgs e)
        {
          string sLine = "";
            using (StreamReader sr = new StreamReader(@"c:\Text.txt"))
            {
                while (!sr.EndOfStream)
                {
                    sLine = sr.ReadLine();
                    listBox1.Items.Add(sLine);
                    
                }
                
               MessageBox.Show("Completed..!");          

            }
        }

Posted 5-Jan-16 11:51am

Member 10410972

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Sergey Alexandrovich Kryukov 5-Jan-16 18:22pm

First of all, what is "ListBox"? Which one? Full type name, please.
But in this case, it's probably not so important. What is your problem?
—SA

2 solutions

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Sergey Alexandrovich Kryukov · Answer 1 · 2016-01-05T12:26:00

Solution 1

On of the possible solution is: couple ListBox with the instance of the class System.Collections.Generic.HashSet<>. You can even create a class derived from ListView. On each add or remove operation, make the content of the set in sync with the items.

Why? Because the time complexity of finding of an item is the set is O(1). Please see:
Big O notation - Wikipedia, the free encyclopedia[^],
Time complexity - Wikipedia, the free encyclopedia[^].

—SA

Posted 5-Jan-16 12:26pm

Sergey Alexandrovich Kryukov

Comments

Member 10410972 6-Jan-16 3:55am

I thought, that if exist any of the same items in Text.txt and listBox1, that such items can not be imported to the listBox1. Thank you.

Sergey Alexandrovich Kryukov 6-Jan-16 9:55am

And..?
Did you actually understand my answer? I did not explain how to check up for existing item, thought it's obvious...
—SA

Member 10410972 · Answer 2 · 2016-01-05T22:48:00

Solution 2

I found a solution. Thanks.

listBox1.Items.AddRange( File.ReadLines( @"C:\Text.txt" ).Distinct().Where( s => ! listBox1.Items.Contains( s )).ToArray() )

Posted 5-Jan-16 22:48pm

Member 10410972