CODEWITHSUNDEEP
c#winformslistviewloops
Jeff Brady
Jeff Brady

Reputation: 1498

How to loop and handle matches vs nonmatches?

I have a ListView with 2 columns. For example's sake, we'll say it looks like this:

ColA    | ColB  
-----------------
001     |  
002     |  
003     |  
004     |  
005     |

I have a text file that contains the following lines:

001  
002  
004  
005  
008

I'm trying to read through the file line by line, and if the number matches a number in ColumnA, I want to add it to ColumnB. That works fine (see my example below). However, I'd also like to add any non-matches as a new ListViewItem. I can't figure that part out. Here's what I have so far:

foreach (string textfileitem in TheTextFile)
{
    foreach (ListViewItem item in ListView1.Items)
    {
        var existingitem = item.SubItems[0];

        if (existingitem.Text == textfileitem)
        {
            item.SubItems[1].Text = textfileitem;
        }
    }
}

I'm not sure how to handle any non-matches and add them to the ListView. the end result would look like this:

ColumnA | ColumnB
----------------- 
001     | 001
002     | 002
003     | 
004     | 004
005     | 005
-       | 008

As always, your help is appreciated!

Upvotes: 0

Views: 135

Answers (4)

Jeff Brady
Jeff Brady

Reputation: 1498

Based on @Neolisk 's suggestion, I rethought my process and ended up using a DataGridView bound to a DataTable. ColumnA gets populated by data in the DataTable. Then, I put each item in ColumnA into a Dictionary.

My code now looks like this:

int count;
Dictionary<string, int> d = new Dictionary<string, int>();

foreach (DataRow dr in dataSet1.Tables["Table1"].Rows)
{
    d.Add((string)dr[0], count);
    count++;
}

foreach (string textfileitem in TheTextFile)
{
    string item = //specific data from textfileitem
    int value;

    if (d.TryGetValue(item, out value)
    {
        DataRow[] dr = dataSet1.Tables["Table1"].Select("ColumnA = " + item");
        dr[0]["ColumnB"] = item;
    }
    else
    {
        dataTable1.Rows.Add(null, item);
    }
}

At least I hope that's accurate. I tried to make my code generic and get rid of the non-essential stuff.

Upvotes: 0

Mike Cofoed
Mike Cofoed

Reputation: 151

I would do something like this:

List<string> listItems = ListView1.Items.Select(item => item[0].ToString())  // Get list of current items
foreach (string textItem in TheTextFile.Except(listItems)) { // Get all text items that are not in the current list
// Add missing list view item
}

Upvotes: 0

Polyfun
Polyfun

Reputation: 9639

Here is another way to do it:

List<string> missingItems = new List<string>();
foreach (string textfileitem in TheTextFile)
{
    foreach (ListViewItem item in ListView1.Items)
    {
        var existingitem = item.SubItems[0];

        if (existingitem.Text == textfileitem)
        {
            item.SubItems[1].Text = textfileitem;
        }
        else
        {
            missingItems.Add(textfileitem);
        }
    }
}
foreach (string missingItem in missingItems)
{
    // Add missing item to your ListView.
    ListView1.Items.Add("missing").SubItems.Add(missingItem);
}

Upvotes: 0

Victor Zakharov
Victor Zakharov

Reputation: 26424

Run through your columnA, create a dictionary of <String,YourDataSourceItem>. Run through your file - test match using TryGetValue. If found, set columnB. If not, create a new item.

Upvotes: 1

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