Develop Reference

Is It possible to find out what are the common part in String List

I was working on finding out the Common string part in the String list. If we take a sample data set
private readonly List<string> Xpath = new List<string>()
{
"BODY>MAIN:nth-of-type(1)>DIV>SECTION>DIV>SECTION>DIV>DIV:nth-of-type(1)>DIV>DIV:nth-of-type(3)>DIV>ARTICLE>DIV>DIV>DIV>SECTION:nth-of-type(1)>H2:nth-of-type(1)",
"BODY>MAIN:nth-of-type(1)>DIV>SECTION>DIV>SECTION>DIV>DIV:nth-of-type(1)>DIV>DIV:nth-of-type(3)>DIV>ARTICLE>DIV>DIV>DIV>SECTION:nth-of-type(2)>H2:nth-of-type(1)",
"BODY>MAIN:nth-of-type(1)>DIV>SECTION>DIV>SECTION>DIV>DIV:nth-of-type(1)>DIV>DIV:nth-of-type(3)>DIV>ARTICLE>DIV>DIV>DIV>SECTION:nth-of-type(3)>H2:nth-of-type(1)",
"BODY>MAIN:nth-of-type(1)>DIV>SECTION>DIV>SECTION>DIV>DIV:nth-of-type(1)>DIV>DIV:nth-of-type(3)>DIV>ARTICLE>DIV>DIV>DIV>SECTION:nth-of-type(4)>H2:nth-of-type(1)",
"BODY>MAIN:nth-of-type(1)>DIV>SECTION>DIV>SECTION>DIV>DIV:nth-of-type(1)>DIV>DIV:nth-of-type(3)>DIV>ARTICLE>DIV>DIV>DIV>SECTION:nth-of-type(5)>H2:nth-of-type(1)",
"BODY>MAIN:nth-of-type(1)>DIV>SECTION>DIV>SECTION>DIV>DIV:nth-of-type(1)>DIV>DIV:nth-of-type(3)>DIV>ARTICLE>DIV>DIV>DIV>SECTION:nth-of-type(6)>H2:nth-of-type(1)",
"BODY>MAIN:nth-of-type(1)>DIV>SECTION>DIV>SECTION>DIV>DIV:nth-of-type(1)>DIV>DIV:nth-of-type(3)>DIV>ARTICLE>DIV>DIV>DIV>SECTION:nth-of-type(7)>H2:nth-of-type(1)",
"BODY>MAIN:nth-of-type(1)>DIV>SECTION>DIV>SECTION>DIV>DIV:nth-of-type(1)>DIV>DIV:nth-of-type(3)>DIV>ARTICLE>DIV>DIV>DIV>SECTION:nth-of-type(8)>H2:nth-of-type(1)",
"BODY>MAIN:nth-of-type(1)>DIV>SECTION>DIV>SECTION>DIV>DIV:nth-of-type(1)>DIV>DIV:nth-of-type(3)>DIV>ARTICLE>DIV>DIV>DIV>SECTION:nth-of-type(9)>H2:nth-of-type(1)"
};
From this, I want to find out to which children these are similar. data is an Xpath list.
Programmatically I should be able to tell
Expected output:
BODY>MAIN:nth-of-type(1)>DIV>SECTION>DIV>SECTION>DIV>DIV:nth-of-type(1)>DIV>DIV:nth-of-type(3)>DIV>ARTICLE>DIV>DIV>DIV
In order to get this What I did was like this. I separate each item by > and then create a list of items for each dataset originally.
Then using this find out what are the unique items
private IEnumerable<T> GetCommonItems<T>(IEnumerable<T>[] lists)
{
HashSet<T> hs = new HashSet<T>(lists.First());
for (int i = 1; i < lists.Length; i++)
{
hs.IntersectWith(lists[i]);
}
return hs;
}
Able to find out the unique values and create a dataset again. But what happened is if this contains Ex:- Div in two places and it also in every originally dataset even then this method will pick up only one Div.
From then I would get something like this:
BODY>MAIN:nth-of-type(1)>DIV>SECTION
But I need this
BODY>MAIN:nth-of-type(1)>DIV>SECTION>DIV>SECTION>DIV>DIV:nth-of-type(1)>DIV>DIV:nth-of-
type(3)>DIV>ARTICLE>DIV>DIV>DIV

Disclaimer: This is not the most performant solution but it works :)
Let's start with splitting the first path by > character
Do the same with all the paths
char separator = '>';
IEnumerable<string> firstPathChunks = Xpath[0].Split(separator);
var chunks = Xpath.Select(path => path.Split(separator).ToList()).ToArray();
Iterate through the firstPathChunks
Iterate through the chunks
if there is a match then remove the first element
if all first element is removed then append the matching prefix to sb
void Process(StringBuilder sb)
{
foreach (var pathChunk in firstPathChunks)
{
foreach (var chunk in chunks)
{
if (chunk[0] != pathChunk)
{
return;
}
chunk.RemoveAt(0);
}
sb.Append(pathChunk);
sb.Append(separator);
}
}
Sample usage
var sb = new StringBuilder();
Process(sb);
Console.WriteLine(sb.ToString());
Output
BODY>MAIN:nth-of-type(1)>DIV>SECTION>DIV>SECTION>DIV>DIV:nth-of-type(1)>DIV>DIV:nth-of-type(3)>DIV>ARTICLE>DIV>DIV>DIV>

Parsing the string by the seperator > is a good idea. Instead of then creating a list of unique items you should create a list of all items contained in the string which would result in
{
"BODY",
"MAIN:nth-of-type(1)",
"DIV",
"SECTTION",
"DIV",
...
}
for the first entry of your XPath list.
This way you create a List<List<string>> containing every element of each entry of your XPath list. You then can compare all first elements of the inner lists. If they are equal save that elements value to you output and proceed with all second elements and so on until you find an element that is not equal in all outer lists.
Edit:
After seperating your list by the > seperator this could look something like this:
List<List<string>> XPathElementsLists;
List<string> resultElements = new List<string>();
string result;
XPathElementsLists = ParseElementsFormXPath(XPath);
for (int i = 0; i < XPathElementsLists[0].Count; i++)
{
bool isEqual = true;
string compareElemment = XPathElementsLists[0][i];
foreach (List<string> element in XPathElementsLists)
{
if (!String.Equals(compareElemment, element))
{
isEqual = false;
break;
}
}
if (!isEqual)
{
break;
}
resultElements.Add(compareElemment);
}
result = String.Join(">", resultElements.ToArray());

Getting number of ITEMS in an array C#

I need to insert a string (from one window(QueryBuilder)) into an array(of another window(Main)).
In the Main i have a method as
public void DisplayCalcQuery(string argFromQueryBuilder)
{
int itemsInUserBuiltQueries = UserBuiltQueries.Count();
UserBuiltQueries[itemsInUserBuiltQueries] = argFromQueryBuilder.ToString();
//displayng the user built query(queries) on the stack panel meant to display it.
foreach (string query in UserBuiltQueries)
{
CheckBox checkQueries = new CheckBox() { Content = query };
stackPanel1.Children.Add(checkQueries);
checkboxes.Add(checkQueries);
}
}
Where UserBuiltQueries is declared as
string[] UserBuiltQueries;
However when from the other window i do
backscreen.DisplayCalcQuery(ttextBox1.Text.ToString()); //where backscreen is the Main
The argument is passed well but i get an error as
{"Value cannot be null.\r\nParameter name: source"}
What did I do wrong ?

These lines are wrong
int itemsInUserBuiltQueries = UserBuiltQueries.Count();
UserBuiltQueries[itemsInUserBuiltQueries] = argFromQueryBuilder.ToString();
Arrays start at index zero and end at index (Count - 1), so, if UserBuiltQueries.Count() returns 10 you could use indexes from 0 to 9. Essentially, using index 10, you are adding a new string outside the end of the array.
However, if your requirements force you to expand the array, it is better and more easy to code if you use a List<string> instead. Adding new elements will be a lot more easier and you could still use the List as an Array for common tasks.
List<string> UserBuiltQueries = new List<string>();
.....
public void DisplayCalcQuery(string argFromQueryBuilder)
{
UserBuiltQueries.Add(argFromQueryBuilder);
//displayng the user built query(queries) on the stack panel meant to display it.
foreach (string query in UserBuiltQueries)
{
CheckBox checkQueries = new CheckBox() { Content = query };
stackPanel1.Children.Add(checkQueries);
checkboxes.Add(checkQueries);
}
}
By the way, you should stop to unnecessarily convert a string to a string. You pass a ttextBox1.Text.ToString() but ttextBox1.Text is already a string. Inside the method the parameter argFromQueryBuilder is already a string and there is no need to convert to a string

Instead of using string[] for UserBuildQueries, use List. When you need it as an array, you can simply say: UserBuildQueries.ToArry()
Rewrite the function to
public void DisplayCalcQuery(string argFromQueryBuilder)
{
UserBuiltQueries.Add(argFromQueryBuilder.ToString());
//displayng the user built query(queries) on the stack panel meant to display it.
foreach (string query in UserBuiltQueries)
{
CheckBox checkQueries = new CheckBox() { Content = query };
stackPanel1.Children.Add(checkQueries);
checkboxes.Add(checkQueries);
}
}

In c# but I think in all programming language indexis start from 0:
so if an array has length or count =1 the index is 0 array[0], array.lenght==1
int itemsInUserBuiltQueries = UserBuiltQueries.Count()-1;
UserBuiltQueries[itemsInUserBuiltQueries] = argFromQueryBuilder.ToString();
And double check that your array is initialized before using it!

Adding to columns based on length

I have a ListView with two columns, Boxes and Files. I'm adding items to a list of strings, and then populating the ListView with that list of strings. I want to make it so all items that are 8 characters long go into the Boxes column and all items that are 9 characters go into the Files column. So far, I've tried to iterate through using a for loop and utilize an if else statement to add the items, but I seem to be doing something wrong. Here's my current code:
public void PopulateItemsList()
{
BoxAndFileList.Items.Clear();
ScanIdBox.Text = string.Empty;
for (int i = 0; i < BoxNumberRepository._boxAndFileList.Count; i++)
{
var item = BoxNumberRepository._boxAndFileList.Item[i];
if (item.Length == 8)
{
BoxAndFileList.Items.Insert(0, item);
}
else
{
BoxAndFileList.Items.Insert(1, item);
}
}
}
I'm iterating through my list (_boxAndFileList) and trying to utilize Insert() to insert items into the specific index of the columns (Boxes is 0, Files is 1). I can clearly see that Item is a legitimate property of a string list, yet VS keeps saying that list contains no definition of it. How can I go about doing this? And also, I haven't received outside feedback on this way of doing things yet, so if there's a better way, please let me know.
Edit: BoxNumberRepository is a class that news up a list called _boxAndFileList. Code below:
public class BoxNumberRepository : Scan_Form
{
public static List<string> _boxAndFileList = new List<string>();
public void AddItem(string item)
{
_boxAndFileList.Add(item);
}
public void Delete(string item)
{
_boxAndFileList.Remove(item);
}
public IEnumerable<string> GetAllItems()
{
return _boxAndFileList;
}
}
Thanks to Alessandro D'Andria for that suggestion. That was correct. However, all the items are still just adding to the first column, even if they're 9 characters. How can I get 9 character items to add to the second column?

The problem that you are having is that you have to add both the box and file to the list item at the same time.
EDIT: Changed cartesian product to a left outer join.
EDIT: Added comments and fixed a syntax bug
private List<string> _boxAndFileList = new List<string> { "12345678", "123456789", "1234", "123456778" };
public void PopulateItemsList()
{
//clear the list
BoxAndFileList.Items.Clear();
//add the labels to the top of the listbox
BoxAndFileList.Columns.Add("Boxes");
BoxAndFileList.Columns.Add("Files");
//set the view of the list to a details view (important if you try to display images)
BoxAndFileList.View = View.Details;
//clear scan id box
ScanIdBox.Text = string.Empty;
//get all the items whos length are 8 as well as a unique id (index)
var boxes = _boxAndFileList.Where(b => b.Length == 8).Select((b, index) => new { index, b }).ToList();
//get all the items whos length are NOT 8 as well as a unique id (index)
var files = _boxAndFileList.Where(f => f.Length != 8).Select((f, index) => new { index, f }).ToList();
//join them together on their unique ids so that you get info on both sides.
var interim = (from f in files
join b in boxes on f.index equals b.index into bf
from x in bf.DefaultIfEmpty()
select new { box = (x == null ? String.Empty : x.b), file = f.f });
//the real trick here is that you have to add
//to the listviewitem of type string[] in order to populate the second, third, or more column.
//I'm just doing this in linq, but var x = new ListViewItem(new[]{"myBox", "myFile"}) would work the same
var fileboxes = interim.Select(x => new ListViewItem(new []{ x.box, x.file})).ToArray();
//add the array to the listbox
BoxAndFileList.Items.AddRange(fileboxes);
//refresh the listbox
BoxAndFileList.Refresh();
}

Your _boxAndFileList is a List<string> so you should be declare item as string type instead var type:
string item = BoxNumberRepository._boxAndFileList.Item[i];
All your code should be like this:
public void PopulateItemsList()
{
BoxAndFileList.Items.Clear();
ScanIdBox.Text = string.Empty;
for (int i = 0; i < BoxNumberRepository._boxAndFileList.Count; i++)
{
string item = BoxNumberRepository._boxAndFileList.Item[i];
if (item.Length == 8)
{
BoxAndFileList.Items.Insert(0, item);
}
else
{
BoxAndFileList.Items.Insert(1, item);
}
}
}

QuickSort void problems

I've been trying to write my own quicksort in C#.
However, when I concatenate the lower, pivot and greater partitions, Visual Studio tells me it cant convert void to string list, though I'm not sure how the concatenated lessList and moreList even becomes void.
Code snippet:
public List<string> SortFiles(List<string> fileList)
{
int listSize = fileList.Count;
if (listSize <= 1)
{
return fileList; //because it is already sorted
}
string pivotString = fileList[listSize/2];
//partition list
List<string> lessList = new List<string>();
List<string> moreList = new List<string>();
foreach (string g in fileList)
{
if (String.Compare(g, pivotString) <= 0)
{
lessList.Add(g);
}
else
{
moreList.Add(g);
}
}
lessList = SortFiles(lessList);
moreList = SortFiles(moreList);
//concatenate lessList + pivot + moreList
List<string> sortedFiles = lessList.Add(pivotString); //thinks is void
sortedFiles = sortedFiles.AddRange(moreList); //thinks is void
return sortedFiles;

The fact is that Add and AddRange don't return a new list with the added element (or range).
Rather, they add the element(s) to the list, modifying it in-place.
In fact you can simply modify the code to just do the Add and AddRange, and it will work.
Note though that it will be rather inefficient, as you are creating lists and copying thing around a lot.

how to dissect string values

How can I dissect or retrieve string values?
Here's the sample code that I'm working on now:
private void SplitStrings()
{
List<string> listvalues = new List<string>();
listvalues = (List<string>)Session["mylist"];
string[] strvalues = listvalues.ToArray();
for (int x = 0; x < strvalues.Length; x++)
{
}
}
Now that I'am able to retrieve list values in my session. How can I separately get the values of each list using foreach or for statement?
What I want to happen is to programmatically split the values of the strings depending on how many is in the list.

If you have a list of string values, you can do the following:
private void SplitStrings()
{
List<string> listValues = (List<string>) Session["mylist"];
// always check session values for null
if(listValues != null)
{
// go through each list item
foreach(string stringElement in listValues)
{
// do something with variable 'stringElement'
System.Console.WriteLine(stringElement);
}
}
}
Note that I test the result of casting the session and that I don't create a new list first-off, which is not necessary. Also note that I don't convert to an array, simply because looping a list is actually easier, or just as easy, as looping an array.
Note that you named your method SplitStrings, but we're not splitting anything. Did you mean to split something like "one;two;three;four" in a four-element list, based on the separator character?

I'm not sure what you're trying to obtain in this code, I don't know why you're converting your List to an Array.
You can loop through your listValues collection with a foreach block:
foreach(string value in listValues)
{
//do something with value, I.e.
Response.Write(value);
}

I don't know what's in the strings but you can start by simplifying. There is no point allocating a new List if you're going to overwrite it immediately.
private void SplitStrings()
{
List<string> list = (List<string>)Session["mylist"];
foreach(string value in list)
{
}
}

List listvalues = (List)Session["mylist"];
foreach (string s in listvalues)
{
//do what you want with s here
}