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Adding a new line in "string.join()" when formatting arrays?

Hello I am a newbie programmer, I am trying to format arrays in a way where there is a line break at the end of a specific set of arrays. I currently have 4 separate arrays in which I want to arrange each item in the array to a specific pattern. I have accomplished this task but now I am stumped because they are all in one line. Let me give you an example: (I am doing this on a datagridview by the way)
(This is what I want to happen)
Binder Clips Small pc 12 1260
Selleys All Clear pc 12 2400
(This is what I am getting)
Binder Clips Small pc 12 1260 Selleys All Clear pc 12 2400
This is my code:
//I get these from a datagridview
var items = carto.Rows
.Cast<DataGridViewRow>()
.Select(x => x.Cells[1].Value.ToString().Trim())
.ToArray();
var units = carto.Rows
.Cast<DataGridViewRow>()
.Select(x => x.Cells[2].Value.ToString().Trim())
.ToArray();
var quantity = carto.Rows
.Cast<DataGridViewRow>()
.Select(x => x.Cells[6].Value.ToString().Trim())
.ToArray();
var prices = carto.Rows
.Cast<DataGridViewRow>()
.Select(x => x.Cells[8].Value.ToString().Trim())
.ToArray();
//this is what I use to sort out the pattern that I want the arrays to be in
string[] concat = new string[items.Length * 4];
int index = 0;
for (int i = 0; i < items.Length; i++)
{
concat[index++] = items[i];
concat[index++] = units[i];
concat[index++] = quantity[i];
concat[index++] = prices[i];
}
// and this is where I am stuck because I can just put \n, it would ruin the format even more
cartitems.Text = string.Join(" ", concat);
I also tried doing something like this:
int j = 0;
string str = "";
foreach (var item in concat)
{
str += item;
if (j <= concat.Length - 1)
{
if (j % 3 == 0)
str += " ";
else
str += "\n";
}
j++;
}
It kinda gets the job done but the line breaks are all over the place.
This is what my projects look like so you can get a better gist on where am I getting the data from the 4 arrays:
basically the product name, unit, quantity and line total
and lastly I am storing in on a label so I can see how it the formatting looks like:
that about sums up my problem, I really hope you can help a newbie like me out, I have a feeling the answer is quite simple and I am just un-experienced.

As a general rule, you should keep your data structures (how the data is stored, implemented here as an array of values) separate from the data representation (in this case, written to a list box).
C# is an object-oriented language, so we might as well take advantage of that, right?
Create a class for your items.
class Item
{
public string Name { get; set; }
public string Unit { get; set; }
public string Quantity { get; set; }
public string Price { get; set; }
override public string ToString() {
return $"{Name} {Unit} {Quantity} {Price}";
}
}
This is how you load your array.
Item[] concat = new Item[items.Length];
int index = 0;
for (int i = 0; i < items.Length; i++) {
concat[index++] = new Item {
Name = items[i],
Unit = units[i],
Quantity = quantity[i],
Price = prices[i]
};
}
and this is how you can add the list of items to a listbox.
foreach(Item item in concat) {
listBox.Items.Add(item);
}

swapping nodes in doubly linked list

Trying to swap the second and third nodes from a doubly linked list in c# with the following method:-
public static void swapNodes(List dblLinkList)
{
Node tempnodeTwo = dblLinkList.firstNode.next; //node two in list
Node tempnodeThree = dblLinkList.firstNode.next.next; //node three in list
Node tempnodeFive = tempnodeTwo.previous;
Node tempnodeSix = tempnodeThree.next;
tempnodeThree.previous = tempnodeFive;
tempnodeThree.next = tempnodeThree;
tempnodeTwo.previous = tempnodeTwo;
tempnodeTwo.next = tempnodeSix;
}
The following shows the output: The first is the original list and the second is the result of the method.
N:19:16 19:16:9 16:9:15 9:15:15 15:15:N
N:19:16 16:16:15 9:15:15 15:15:N
Where am I going wrong?? I have already studied previous questions about this topic which gave me the idea for the code but now stuck!

It seems that you assume tempnodeThree is the third and tempnodeTwo is the second node
of the linked list regardless of the changes you make but this is not the case.
After the initializations what you get is:
tempnodeFive <--> tempnodeTwo <--> tempnodeThree <--> tempnodeSix
And you need is:
tempnodeFive <--> tempnodeThree <--> tempnodeTwo <--> tempnodeSix
So what you have to change from left to right are:
tempNodeFive.next, tempNodeTwo.previous, tempNodeTwo.next, tempNodeThree.previous, tempNodeThree.next, tempNodeSix.previous
Let's go over them following the 2nd linked list representation:
tempNodeFive.next = tempNodeThree;
tempNodeTwo.previous = tempnodeThree;
tempNodeTwo.next = tempnodeSix;
tempNodeThree.previous = tempnodeFive;
tempNodeThree.next = tempnodeTwo;
tempNodeSix.previous = tempnodeTwo;
These six lines are what you need.
PS: You can reconsider variable names for a readable and maintainable code, esp. tempNodeFive and tempnodeSix because five and six does not make any sense as an index and it arises confusion while reading the code.

well here in these lines
tempnodeThree.next = tempnodeThree;
tempnodeTwo.previous = tempnodeTwo;
you are setting the next of a node to itself and the previous of another to itself.
don't you mean
tempnodeThree.next = tempnodeTwo;
tempnodeTwo.previous = tempnodeThree;
I think you would have an easier time if you used better names.
I also would not implement this function like this -- I'd make the function suit it's name like this:
public static void swapNodes(Node a, Node b)
{
if (a == null) return;
if (b == null) return;
Node afterA = a.next;
Node beforeA = a.previous;
a.previous = b.previous;
if (b.previous != null) b.previous.next = a;
a.next = b.next;
if (b.next != null) b.next.previous = a;
b.next = afterA;
if (afterA != null) afterA.previous = b;
b.previous = beforeA;
if (beforeA != null) beforeA.next = b;
}
// call it like this
swapNodes(dblLinkList.firstNode.next, dblLinkList.firstNode.next.next);

Are you sure it's c#? Looks like java. C# has LinkedListNode<T> class, not Node. And LinkedListNode<T> has Next and Previous properties. With capitals. And they are read only.
Any way c# implementation looks like this:
using System;
using System.Collections.Generic;
namespace LinkedListSwap
{
class Program
{
static void Main(string[] args)
{
var list = new LinkedList<string>(new[] { "1st", "2nd", "3rd", "4th", "5th", "6th", "7th" });
Console.WriteLine(list.ToDisplayString());
list.Swap(2, 3);
Console.WriteLine(list.ToDisplayString());
}
}
static class LinkedListExtensions
{
public static void Swap<T>(this LinkedList<T> list, int firstIndex, int secondIndex)
{
if (firstIndex < 1 || firstIndex > list.Count)
throw new IndexOutOfRangeException($"Index out of range: {nameof(firstIndex)}");
if (secondIndex < 1 || secondIndex > list.Count)
throw new IndexOutOfRangeException($"Index out of range: {nameof(secondIndex)}");
if (firstIndex == secondIndex)
return;
if (firstIndex > secondIndex)
(firstIndex, secondIndex) = (secondIndex, firstIndex);
int i = 0;
var leftNode = list.First;
while (++i < firstIndex)
leftNode = leftNode.Next;
var rightNode = leftNode.Next;
while (++i < secondIndex)
rightNode = rightNode.Next;
list.Replace(leftNode, rightNode);
list.Replace(rightNode, leftNode);
}
public static void Replace<T>(this LinkedList<T> list, LinkedListNode<T> oldNode, LinkedListNode<T> newNode)
{
list.AddAfter(oldNode, new LinkedListNode<T>(newNode.Value));
list.Remove(oldNode);
}
public static string ToDisplayString<T>(this LinkedList<T> list) => string.Join(" ", list);
}
}
Output is:
1st 2nd 3rd 4th 5th 6th 7th
1st 3rd 2nd 4th 5th 6th 7th

How to compare sequential elements in a foreach loop in C#

In a foreach loop I want to compare an element with the previous element that was read. How can I do that? What is the syntax for addressing a previous element in a foreach loop?

You don't have that option built in with a foreach loop.
You can either switch to a for loop or use a variable.
Suppose you iterate through a list of objects, these are your options:
object prev = null;
foreach(var current in myListOfObjects)
{
if(current == prev)
{
// do stuff
}
// don't forget the next row!
prev = current;
}
or
for(var i = 1; i < myListOfObjects.count, i++) // Note: starting from 1 to avoid another condition inside the loop.
{
if(myListOfObjects[i] == myListOfObjects[i-1])
{
// do stuff
}
}

Everything is better with Bluetooth extension methods:
public static class EnumerableExtensions
{
public struct CurrentAndPrevious<T>
{
public T Current { get; private set; }
public T Previous { get; private set; }
public CurrentAndPrevious(T current, T previous) : this()
{
Previous = previous;
Current = current;
}
}
public static IEnumerable<CurrentAndPrevious<T>> WithPrevious<T>(this IEnumerable<T> enumerable)
{
var previous = default(T);
using(var enumerator = enumerable.GetEnumerator())
{
while(enumerator.MoveNext())
{
yield return new CurrentAndPrevious<T>(enumerator.Current, previous);
previous = enumerator.Current;
}
}
}
}
var items = new[] { 1, 2, 3, 4, 5 };
foreach(var item in items.WithPrevious())
{
Console.WriteLine(item.Previous + " " + item.Current);
}
You might need to tweak this depending on how you want first and last elements handled.

You can loop over a bit modified source instead of initial, say ListOfMyObjects:
MyObject prior = default(MyObject);
var source = ListOfMyObjects
.Select(item => {
var result = new {
Current = item,
Prior = prior,
};
prior = item; // side effect, not a good practice
return result;
});
So you can loop
foreach(var item in source) {
if (item.Prior == item.Current) {
...
}
}

A foreach itself has no syntax 'for addressing a previous element'. There are two options, depending on the characteristics of the collection and also the notion of a 'previous' element in respect of the first one. The following the examples are a little bit simplistic, but you should be able to choose the right path and fine-tune the details.
Option 1: Use a temporary variable
Works well if there's no cheap (performance-wise) way to index elements in the sequence, and you are OK with 'pretending' there's an empty (null, or default(T)) item before the very first item.
T previous = default(T); // corresponds to null for reference types
foreach (T item in sequence)
{
… work with previous and item here…
// the current 'item' is the new 'previous' for the next iteration
previous = item;
}
Note that if T is a value type, your would be actually copying the values themselves.
Option 2: Use a for loop and indexing
Works well if there is a cheap (performance-wise) way to index individual elements directly. List<T> and arrays are good examples here.
// indexing from 1, i.e. from the second item in the sequence
for (int i = 1; i < sequence.Count; i++)
{
var previous = sequence[i-1]; // this is obviously the previous item
var current = sequence[i]; // this is obviously the current item
}

Similar to using a temp variable, however this solution moves the scope of the temp variable inside the loop
var collection = new List<int>() { 1, 2, 3, 4, 5 };
foreach (var item in collection)
{
var currentIndex = collection.IndexOf(item);
if (currentIndex > 0 && currentIndex < collection.Count)
{
var previousItem = collection[currentIndex - 1];
}
}

As mentioned by Pham X, one easy way to do this would be a temp variable.
ObjectType temp_object = null;
foreach(var entry in ListOfObjects)
{
if(temp_object==null)
{
//this is the first time through...
temp_object=entry;
}
else
{
//it's anything after the first loop
if(entry==temp_object) Console.WriteLine("There is a match between two entries.");
else temp_object=entry;
}
}

How to count occurences of number stored in file containing multiple delimeters?

This is my input store in file:
50|Carbon|Mercury|P:4;P:00;P:1
90|Oxygen|Mars|P:10;P:4;P:00
90|Serium|Jupiter|P:4;P:16;P:10
85|Hydrogen|Saturn|P:00;P:10;P:4
Now i will take my first row P:4 and then next P:00 and then next like wise and want to count occurence in every other row so expected output will be:
P:4 3(found in 2nd row,3rd row,4th row(last cell))
P:00 2 (found on 2nd row,4th row)
P:1 0 (no occurences are there so)
P:10 1
P:16 0
etc.....
Like wise i would like to print occurence of each and every proportion.
So far i am successfull in splitting row by row and storing in my class file object like this:
public class Planets
{
//My rest fields
public string ProportionConcat { get; set; }
public List<proportion> proportion { get; set; }
}
public class proportion
{
public int Number { get; set; }
}
I have already filled my planet object like below and Finally my List of planet object data is like this:
List<Planets> Planets = new List<Planets>();
Planets[0]:
{
Number:50
name: Carbon
object:Mercury
ProportionConcat:P:4;P:00;P:1
proportion[0]:
{
Number:4
},
proportion[1]:
{
Number:00
},
proportion[2]:
{
Number:1
}
}
Etc...
I know i can loop through and perform search and count but then 2 to 3 loops will be required and code will be little messy so i want some better code to perform this.
Now how do i search each and count every other proportion in my planet List object??

Well, if you have parsed proportions, you can create new struct for output data:
// Class to storage result
public class Values
{
public int Count; // count of proportion entry.
public readonly HashSet<int> Rows = new HashSet<int>(); //list with rows numbers.
/// <summary> Add new proportion</summary>
/// <param name="rowNumber">Number of row, where proportion entries</param>
public void Increment(int rowNumber)
{
++Count; // increase count of proportions entries
Rows.Add(rowNumber); // add number of row, where proportion entry
}
}
And use this code to fill it. I'm not sure it's "messy" and don't see necessity to complicate the code with LINQ. What do you think about it?
var result = new Dictionary<int, Values>(); // create dictionary, where we will storage our results. keys is proportion. values - information about how often this proportion entries and rows, where this proportion entry
for (var i = 0; i < Planets.Count; i++) // we use for instead of foreach for finding row number. i == row number
{
var planet = Planets[i];
foreach (var proportion in planet.proportion)
{
if (!result.ContainsKey(proportion.Number)) // if our result dictionary doesn't contain proportion
result.Add(proportion.Number, new Values()); // we add it to dictionary and initialize our result class for this proportion
result[proportion.Number].Increment(i); // increment count of entries and add row number
}
}

You can use var count = Regex.Matches(lineString, input).Count;. Try this example
var list = new List<string>
{
"50|Carbon|Mercury|P:4;P:00;P:1",
"90|Oxygen|Mars|P:10;P:4;P:00",
"90|Serium|Jupiter|P:4;P:16;P:10",
"85|Hydrogen|Saturn|P:00;P:10;P:4"
};
int totalCount;
var result = CountWords(list, "P:4", out totalCount);
Console.WriteLine("Total Found: {0}", totalCount);
foreach (var foundWords in result)
{
Console.WriteLine(foundWords);
}
public class FoundWords
{
public string LineNumber { get; set; }
public int Found { get; set; }
}
private List<FoundWords> CountWords(List<string> words, string input, out int total)
{
total = 0;
int[] index = {0};
var result = new List<FoundWords>();
foreach (var f in words.Select(word => new FoundWords {Found = Regex.Matches(word, input).Count, LineNumber = "Line Number: " + index[0] + 1}))
{
result.Add(f);
total += f.Found;
index[0]++;
}
return result;
}

I made a DotNetFiddle for you here: https://dotnetfiddle.net/z9QwmD
string raw =
#"50|Carbon|Mercury|P:4;P:00;P:1
90|Oxygen|Mars|P:10;P:4;P:00
90|Serium|Jupiter|P:4;P:16;P:10
85|Hydrogen|Saturn|P:00;P:10;P:4";
string[] splits = raw.Split(
new string[] { "|", ";", "\n" },
StringSplitOptions.None
);
foreach (string p in splits.Where(s => s.ToUpper().StartsWith(("P:"))).Distinct())
{
Console.WriteLine(
string.Format("{0} - {1}",
p,
splits.Count(s => s.ToUpper() == p.ToUpper())
)
);
}
Basically, you can use .Split to split on multiple delimiters at once, it's pretty straightforward. After that, everything is gravy :).
Obviously my code simply outputs the results to the console, but that part is fairly easy to change. Let me know if there's anything you didn't understand.

Creating a two-dimensional array

I am trying to create a two dimensional array and I am getting so confused. I was told by a coworker that I need to create a dictionary within a dictionary for the array list but he couldn't stick around to help me.
I have been able to create the first array that lists the the programs like this
+ project 1
+ project 2
+ project 3
+ project 4
The code that accomplishes this task is below-
var PGList = from x in db.month_mapping
where x.PG_SUB_PROGRAM == SP
select x;
//select x.PG.Distinct().ToArray();
var PGRow = PGList.Select(x => new { x.PG }).Distinct().ToArray();
So that takes care of my vertical array and now I need to add my horizontal array so that I can see the total amount spent in each accounting period. So the final output would look like this but without the dashes of course.
+ program 1-------100---200---300---400---500---600---700---800---900---1000---1100---1200
+ program 2-------100---200---300---400---500---600---700---800---900---1000---1100---1200
+ program 3-------100---200---300---400---500---600---700---800---900---1000---1100---1200
+ program 4-------100---200---300---400---500---600---700---800---900---1000---1100---1200
I have tried to use a foreach to cycle through the accounting periods but it doesn't work. I think I might be on the right track and I was hoping SO could provide some guidance or at the very least a tutorial for me to follow. I have posted the code that I written so far on the second array below. I am using C# and MVC 3. You might notice that their is no dictionary within a dictionary. If my coworker is correct how would I do something like that, I took a look at this question using dictionary as a key in other dictionary but I don't understand how I would use it in this situation.
Dictionary<string, double[]> MonthRow = new Dictionary<string, double[]>();
double[] PGContent = new double[12];
string lastPG = null;
foreach (var item in PGRow)
{
if (lastPG != item.PG)
{
PGContent = new double[12];
}
var MonthList = from x in db.Month_Web
where x.PG == PG
group x by new { x.ACCOUNTING_PERIOD, x.PG, x.Amount } into pggroup
select new { accounting_period = pggroup.Key.ACCOUNTING_PERIOD, amount = pggroup.Sum(x => x.Amount) };
foreach (var P in MonthList)
{
int accounting_period = int.Parse(P.accounting_period) - 1;
PAContent[accounting_period] = (double)P.amount;
MonthRow[item.PG] = PGContent;
lastPG = item.PG;
}
I hope I have clearly explained my issue, please feel free to ask for any clarification needed as I need to solve this problem and will be checking back often. Thanks for your help!

hope this helps.
// sample data
var data = new Dictionary<string, List<int>>();
data.Add("program-1", new List<int>() { 100, 110, 130 });
data.Add("program-2", new List<int>() { 200, 210, 230 });
data.Add("brogram-3", new List<int>() { 300, 310, 330 });
// query data
var newData = (from x in data
where x.Key.Contains("pro")
select x).ToDictionary(v => v.Key, v=>v.Value);
// display selected data
foreach (var kv in newData)
{
Console.Write(kv.Key);
foreach (var val in kv.Value)
{
Console.Write(" ");
Console.Write(val.ToString());
}
Console.WriteLine();
}
output is:
program-1 100 110 130
program-2 200 210 230

Don't try to use anonymous types or LINQ projection to create new data types, especially if you're a beginner, you will just get confused. If you want a specialized data type, define one; e.g.:
public class Account
{
public string Name { get; private set; }
public decimal[] MonthAmount { get; private set; }
readonly int maxMonths = 12;
public Account(string name, ICollection<decimal> monthAmounts)
{
if (name == null)
throw new ArgumentNullException("name");
if (monthAmounts == null)
throw new ArgumentNullException("monthAmounts");
if (monthAmounts.Count > maxMonths)
throw new ArgumentOutOfRangeException(string.Format(" monthAmounts must be <= {0}", maxMonths));
this.Name = name;
this.MonthAmount = new decimal[maxMonths];
int i = 0;
foreach (decimal d in monthAmounts)
{
this.MonthAmount[i] = d;
i++;
}
}
}
Use instances of this type directly, you do not have to convert them to arrays, dictionaries, lists, or anything else:
var accountPeriods = new List<Account>();
accountPeriods.Add(new Account("program-1", new decimal[] { 1, 2, 3, 4 }));
You can use LINQ or whatever to query or alter instances of your new type:
foreach (Account a in accountPeriods)
foreach (decimal d in a.MonthAmount)
DoSomethingWith(d);
That should be enough to get you started.

I want to thank #Ray Cheng and #Dour High Arch for their help but I have figured out another way to accomplish this task and I wanted to post my code so that the next person that is having the same trouble can figure out their problem faster.
Above I split my code into more managable sections to explain my problem as clearly as I could and the code below has all those parts combined so you can see the big picture. This code returns an array that contains the program and the amounts for every month.
public virtual ActionResult getAjaxPGs(string SP = null)
{
if (SP != null)
{
var PGList = from x in db.month_mapping
where x.PG_SUB_PROGRAM == SP
select x;
var PGRow = PGList.Select(x => new { x.PG }).Distinct().ToArray();
float[] PGContent = new float[12];
Dictionary<string,float[]> MonthRow = new Dictionary<string, float[]>();
foreach (var item in PGRow)
{
PGContent = new float[12];
var MonthList = from x in db.month_Web
where x.PG == item.PG
group x by new { x.ACCOUNTING_PERIOD, x.PG, x.Amount } into pggroup
select new { accounting_period = pggroup.Key.ACCOUNTING_PERIOD, amount = pggroup.Sum(x => x.Amount) };
foreach (var mon in MonthList)
{
int accounting_period = int.Parse(mon.accounting_period) - 1;
PGContent[accounting_period] = (float)mon.amount/1000000;
}
MonthRow[item.PG] = PGContent;
}
return Json(MonthRow, JsonRequestBehavior.AllowGet);
}
return View();
}
This code worked great for me since I am pulling from a Linq to SQL query instead of adding data directly into the code. My problems stemmed from mainly putting the data pulls outside of the foreach loops so it only pulled 1 piece of data from the SQL instead of all twelve months. I hope this helps some one else who is trying to pull data in from SQL data sources into multidimensional arrays.