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Hi, I am trying to write a program that searches a text file for multiple keywords, then lists the matches in a ListBox.

The text file I am testing this on has contents of: this is. not a test

I have the matching right but I am having trouble getting a string to show up from LINQ. With the code I have below, only the last match will show up on the ListBox because the for loop assigns a new value to 'matches' every time.

Anything else I try ends up showing "(Collection)" or something that ends in "[System.String]" for each match.

I apologize if I am unclear; I am new to this. I have searched all over and just want to add the results to a list but I can't find anything that works.

If only "select word.ToString()" worked I could do listBox1.Items.Add(matches);
But, that doesn't work either. I would very much appreciate some help on this.


C#
List<string> matches = new List<string>();

string sourceText = System.IO.File.ReadAllText(fileName);

string[] words = sourceText.Split(new char[] { '.', '?', '!', ',', ' ',
    ';', '\'', ':', '"', '-' }, StringSplitOptions.RemoveEmptyEntries);

string[] wordsToMatch = { "this", "is", "a", "test" };

for (int i = 0; i < wordsToMatch.Count(); i++)
{
    matches = (from word in words
             where word.ToLowerInvariant() == wordsToMatch[i].ToLowerInvariant()
             select word).ToList();
 }

foreach (string s in matches)
{
    listBox1.DataSource = matches;
}
Posted

Change your code as following--
C#
List <string> matches = new List<string>();
 
string sourceText = System.IO.File.ReadAllText(fileName);
 
string[] words = sourceText.Split(new char[] { '.', '?', '!', ',', ' ',
    ';', '\'', ':', '"', '-' }, StringSplitOptions.RemoveEmptyEntries);
 
List<string> wordsToMatch = new List<string>(new string[] { "this", "is", "a", "test" });
 
 matches = (from word in words
             where wordsToMatch.Contains(word.ToLowerInvariant())
             select word).ToList();
 
    foreach (string s in matches)
    {
      listBox1.Items.Add(s);
    }

//or now you can use
//listBox1.DataSource=matches;
// but loop is not required in this case.
 
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v3
I assume you are messing with LINQ and strings sample[^] or a similar one in there.
Anyway, change following

C#
string[] wordsToMatch = { "this", "is", "a", "test" };
for (int i = 0; i < wordsToMatch.Count(); i++)
{
    matches = (from word in words
             where word.ToLowerInvariant() == wordsToMatch[i].ToLowerInvariant()
             select word).ToList();
 }
foreach (string s in matches)
{
    listBox1.DataSource = matches;
}


to
C#
List<string> wordsToMatch = new List<string>()
wordsToMatch.AddRange(new string[]{ "this", "is", "a", "test" });
string[] matches = (from word in words
         where wordsToMatch.Contains(word)
         select word).ToArray();
listBox1.DataSource = matches;
</string></string>
 
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Thank you two very much for your help. :)
 
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v2

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