Develop Reference

Not able to initiate the List<customer>. The value of Customers.Names is null

using System;
using System.Collections.Generic;
using ConsoleApp3;
namespace ConsoleApp3
{
class Program
{
static void Main(string[] args)
{
Customers customers = new Customers();
List<Customers> names = new List<Customers>()
{
new Customers {Names = "Tanveer"},
new Customers {Names = "Nabila"},
new Customers {Names = "Suraj"}
};
foreach (int i = 0; i < names.Count; i++)
{
Console.WriteLine(customers.Names.Length);
}
}
class Customers
{
public string Names { get; set; }
}
}
}
I want to create the list of Customers and write it on the Console. But the Customers.Names is null. I am new to programming so please help.Thanks

First, let us fix up that naming. Naming is very important, but also one of the more annoying parts.
//Singular for the class
class Customer
{
//Also Singular, as this can only take 1 name
public string Name { get; set; }
}
//Plural, because it is a collection of Customer Instances.
List<Customer> Customers = new List<Customer>()
{
new Customer {Name = "Tanveer"},
new Customer {Name = "Nabila"},
new Customer {Name = "Suraj"}
};
Then you itterate over it using:
//Use a proper foreach, no need to deal with Indexes here
foreach (Customer current in Customers){
Console.WriteLine(current.Name);
}
If you do want to have a running counter, this is how the loop would look:
for(int i = 0; i < Customers.Count;i++){
//I you get any Exceptions, you want to split it up over 2 lines using a temporary variable
Console.WriteLine(Customers[i].Name);
}
What you had in your code was a bastardisation of for and foreach syntax, wich I doubt compiled.

Console.WriteLine(names[i].Names);

customers.Names is null because customers is an object which you haven't populated with any data, and has no obvious purpose. names is the actual list of customers with useful info in it.
names does not have a Names property directly either, though. The objects within the list do. So you need to refer to a specific object within the specific list.
And since you're in a loop for doing just that, names[i].Names.Length is no doubt what you intended.
N.B. However it needs to be a for rather than foreach in the loop definition - the syntax used with foreach is different. This shouldn't have compiled in order to allow you to even see the null output, so perhaps this is just a typo in your posted code.
for (int i = 0; i < names.Count; i++)
{
Console.WriteLine(names[i].Names.Length);
}
should be closer to what you need (although I'm not convinced you really are intending to print the length of each name...but that's up to you).
P.S. You should probably amend your naming convention so you've got Customer as the type and Name as the property. It's much more readable and comprehensible if they're singular rather than plural.

Working with XML under C# - Difficulties

it's me again. This time, having some issues with XML. I had everything working in VB.NET (I'll show all the code I used later) but now I'm developing something else for VB application except I'm using C# for it. Part of this involves reading an XML and populating something specific into a ListBox and then being able to click on it and get the attributes for use in other controls (description loads to a text box, etc, you'll see).
I can't seem to figure out XML for the life of me in C# however. In VB, I did it like this:
Dim games() As String = xml...<episode>.Select(Function(n) n.Value).ToArray
AvailableEpisodes.DataSource = games
Where "AvailableEpisodes" is the ListBox I wish to populate. This displayed the "This is a test" term: This is a test
And then this is the SelectedIndexChanged code:
Dim node As XElement = xml...<episode>.First(Function(n) n.Value = AvailableEpisodes.Text)
DescriptionTextBox.Text = node.#Description
AuthorTextBox.Text = node.#Author
generatedDownloadLink = node.#DownloadLink
generatedTechName = node.#TechName
IconImage.ImageLocation = node.#IconLoc
What exactly would be the C# equivalent of this? I already tried copy-pasting (just figured I'd try it) and a couple code converters and none of them seem to work.
The goal of this application will be to be able to double click on the selected index and load these strings into another window (which I can work out by attaching the nodes to a string variable) I just need to get started.
Code I've tried:
using (XmlReader reader = XmlReader.Create(testXml))
{
while (reader.Read())
{
if ((reader.NodeType == XmlNodeType.Element) && reader.Name == "episode")
{
listBox1.DataSource = reader.GetAttribute("TechName").ToList();
}
}
}
But that literally just outputs this: http://imgur.com/Naeabf9.png
Any extra information I'll toss in an edit or a reply
Thanks in advanced,
Mike

Its easy: ... corresponds to Descendants. <foo> corresponds to element name. #bar corresponds to attribute name.
var xml = XDocument.Load(path_to_xml);
var node = xml.Descendants("episode")
.First(n => n.Value == AvailableEpisodes.Text);
DescriptionTextBox.Text = (string)node.Attribute("Description");
AuthorTextBox.Text = (string)node.Attribute("Author");
generatedDownloadLink = (string)node.Attribute("DownloadLink");
generatedTechName = (string)node.Attribute("TechName");
IconImage.ImageLocation = (string)node.Attribute("IconLoc");
Note - if there is no matching node, then First will throw exception. Usually you should use FirstOrDefault in such case and then check node for null.

Is "This is a test" supposed to be one single item in the ListBox? If it is, your logic in the C# code is wrong. Indeed, reader.GetAttribute("TechName").ToList() will return an array like this
["T","h","i", "s", " ", "i", "s", " ", "t", "e", "s", "t"]
Therefore, the text gets broken up into many items in the ListBox.
To read all nodes in the xml documents into ListBox, you have to create a temporary list to hold all the results read from the xml, then at the end bind the list to ListBox listBox1.DataSource = results

Why don't you just use XML Serialization?
Assuming your XML looks something like this:
<EpisodeData>
<Episodes>
<Episode Description="..." Author="..." DownloadLink="..." ... />
<Episode Description="..." Author="..." DownloadLink="..." ... />
<Episode Description="..." Author="..." DownloadLink="..." ... />
</Episodes>
</EpisodeData>
Create classes in C# that represents the data. Something like this:
[Serializable]
public class EpisodeData
{
[XmlArray("Episodes")]
[XmlArrayItem(ElementName = "Episode")]
List<Episode> Episodes { get; set; }
}
[Serializable]
public class Episode
{
[XmlAttribute]
public string Description { get; set; }
[XmlAttribute]
public string Author { get; set; }
[XmlAttribute]
public string DownloadLink { get; set; }
...
}
Then you can deserialize and use the data like this:
EpisodeData data;
XmlSerializer serializer = new XmlSerializer(typeof(EpisodeData));
using (StreamReader sr = new StreamReader(fileName))
{
data = (EpisodeData)serializer.Deserialize(sr);
}
// Assuming you only want to see the description. If you want something else
// you might want to use a DataGrid to bind to each property in Episode or
// override ToString in Episode.
List<string> descriptions = new List<string>();
foreach (Episode episode in data.Episodes)
{
descriptions.Add(episode.Description);
}
listBox1.DataSource = descriptions;
More info on XML Serialization here:
http://msdn.microsoft.com/en-us/library/58a18dwa(v=vs.110).aspx

Get a single element of CSV file

I'm trying to add some csv elements to a list of Alimento, where Alimento is declared as:
namespace ContaCarboidrati
{
class Alimento
{
public virtual string Codice { get; set; }
public virtual string Descrizione { get; set; }
public virtual int Carboidrati { get; set; }
}
}
My csv looks something like this:
"C00, Pasta, 75".
Here's the method that should create the list from the csv:
private static List<Alimento> CreaListaAlimentiDaCsv()
{
List<Alimento> listaCsv = new List<Alimento>();
StreamReader sr = new StreamReader(#"C:\Users\Alex\Documents\RecordAlimenti.csv");
string abc = sr.ReadLine();
//listaCsv = abc.Split(",");
}
abc is "C00, Pasta, 75". I want to get a single element to add it to the list, or add all the 3 elements to the list, i thought that a single element is easier to made.
Sorry for my bad English
Thanks in advance
Alex

You are on the right track, but you cannot just create an Alimento of three strings, which is what you will get if you do abc.Split(","). You need to create a new Alimento object for each item (line) in the csv file and initialize each object correctly. Something like this:
var item = abc.Split(',');
listaCsv.Add(new Alimento() { Codice = item[0], Descrizione = item[1],
Carboidrati = int.Parse(item[2])};
Also, your csv seems to include spaces after the commas which you might want to get rid of. You could use string.Trim() to get rid of leading/trailing spaces. You also have to make sure the third item is actually an integer and take action if that is not the case (i.e. add some error handling).
As a side note, implementing a csv reader is not as trivial as one may think, but there are several free C# implementations out there. If you need something a bit more advanced than just reading a simple (and strictly one-line-per-item) csv, try one of these:
http://www.codeproject.com/Articles/9258/A-Fast-CSV-Reader
http://www.filehelpers.com/

You can parse file with LINQ
var listaCsv = (from line in File.ReadAllLines("RecordAlimenti.csv")
let items = line.Split(',')
select new Alimento {
Codice = items[0],
Descrizione = items[1],
Carboidrati = Int32.Parse(items[2])
}).ToList();

You can parse it pretty easy assuming your data isn't bad.
private IEnumerable<Alimento> CreaListaAlimentiDaCsv(string fileName)
{
return File.Readlines(fileName) //#"C:\Users\Alex\Documents\RecordAlimenti.csv"
.Select(line => line.Split(',').Trim())
.Select(
values =>
new Alimento
{
Codice = value[0],
Descrizione = values[0],
Carboidrati = Convert.ToInt32(values[3])
});
}
You can also use Linq on the method such as
//Takes one line without iterating the entire file
CreaListaAlimentiDaCsv(#"C:\Users\Alex\Documents\RecordAlimenti.csv").Take(1);
//Skips the first line and takes the second line reading two lines total
CreaListaAlimentiDaCsv(#"C:\Users\Alex\Documents\RecordAlimenti.csv").Skip(1).Take(1);

Parsing a CSV formatted text file

I have a text file that looks like this:
1,Smith, 249.24, 6/10/2010
2,Johnson, 1332.23, 6/11/2010
3,Woods, 2214.22, 6/11/2010
1,Smith, 219.24, 6/11/2010
I need to be able to find the balance for a client on a given date.
I'm wondering if I should:
A. Start from the end and read each line into an Array, one at a time.
Check the last name index to see if it is the client we're looking for.
Then, display the balance index of the first match.
or
B. Use RegEx to find a match and display it.
I don't have much experience with RegEx, but I'll learn it if it's a no brainer in a situation like this.

I would recommend using the FileHelpers opensource project:
http://www.filehelpers.net/
Piece of cake:
Define your class:
[DelimitedRecord(",")]
public class Customer
{
public int CustId;
public string Name;
public decimal Balance;
[FieldConverter(ConverterKind.Date, "dd-MM-yyyy")]
public DateTime AddedDate;
}
Use it:
var engine = new FileHelperAsyncEngine<Customer>();
// Read
using(engine.BeginReadFile("TestIn.txt"))
{
// The engine is IEnumerable
foreach(Customer cust in engine)
{
// your code here
Console.WriteLine(cust.Name);
// your condition >> add balance
}
}

This looks like a pretty standard CSV type layout, which is easy enough to process. You can actually do it with ADO.Net and the Jet provider, but I think it is probably easier in the long run to process it yourself.
So first off, you want to process the actual text data. I assume it is reasonable to assume each record is seperated by some newline character, so you can utilize the ReadLine method to easily get each record:
StreamReader reader = new StreamReader("C:\Path\To\file.txt")
while(true)
{
var line = reader.ReadLine();
if(string.IsNullOrEmpty(line))
break;
// Process Line
}
And then to process each line, you can split the string on comma, and store the values into a data structure. So if you use a data structure like this:
public class MyData
{
public int Id { get; set; }
public string Name { get; set; }
public decimal Balance { get; set; }
public DateTime Date { get; set; }
}
And you can process the line data with a method like this:
public MyData GetRecord(string line)
{
var fields = line.Split(',');
return new MyData()
{
Id = int.Parse(fields[0]),
Name = fields[1],
Balance = decimal.Parse(fields[2]),
Date = DateTime.Parse(fields[3])
};
}
Now, this is the simplest example, and doesn't account for cases where the fields may be empty, in which case you would either need to support NULL for those fields (using nullable types int?, decimal? and DateTime?), or define some default value that would be assigned to those values.
So once you have that you can store the collection of MyData objects in a list, and easily perform calculations based on that. So given your example of finding the balance on a given date you could do something like:
var data = customerDataList.First(d => d.Name == customerNameImLookingFor
&& d.Date == dateImLookingFor);
Where customerDataList is the collection of MyData objects read from the file, customerNameImLookingFor is a variable containing the customer's name, and customerDateImLookingFor is a variable containing the date.
I've used this technique to process data in text files in the past for files ranging from a couple records, to tens of thousands of records, and it works pretty well.

I think the cleanest way is to load the entire file into an array of custom objects and work with that. For 3 MB of data, this won't be a problem. If you wanted to do completely different search later, you could reuse most of the code. I would do it this way:
class Record
{
public int Id { get; protected set; }
public string Name { get; protected set; }
public decimal Balance { get; protected set; }
public DateTime Date { get; protected set; }
public Record (int id, string name, decimal balance, DateTime date)
{
Id = id;
Name = name;
Balance = balance;
Date = date;
}
}
…
Record[] records = from line in File.ReadAllLines(filename)
let fields = line.Split(',')
select new Record(
int.Parse(fields[0]),
fields[1],
decimal.Parse(fields[2]),
DateTime.Parse(fields[3])
).ToArray();
Record wantedRecord = records.Single
(r => r.Name = clientName && r.Date = givenDate);

Note that both your options will scan the file. That is fine if you only want to search in the file for 1 item.
If you need to search for multiple client/date combinations in the same file, you could parse the file into a Dictionary<string, Dictionary <date, decimal>> first.
A direct answer: for a one-off, a RegEx will probably be faster.

If you're just reading it I'd consider reading in the whole file in memory using StreamReader.ReadToEnd and then treating it as one long string to search through and when you find a record you want to look at just look for the previous and next line break and then you have the transaction row you want.
If it's on a server or the file can be refreshed all the time this might not be a good solution though.

If it's all well-formatted CSV like this then I'd use something like the Microsoft.VisualBasic.TextFieldParser class or the Fast CSV class over on code project to read it all in.
The data type is a little tricky because I imagine not every client has a record for every day. That means you can't just have a nested dictionary for your looksup. Instead, you want to "index" by name first and then date, but the form of the date record is a little different. I think I'd go for something like this as I read in each record:
Dictionary<string, SortedList<DateTime, double>>

hey, hey, hey!!! why not do it with this great project on codeproject Linq to CSV, way cool!
rock solid

Doubled tags for one property in ROWLEX

I have this code:
[RdfSerializable( HasResourceUri=false )]
public class Item
{
[RdfProperty(true)]
public string MyProp;
}
[RdfSerializable]
public class AllItems
{
[RdfProperty(true)] public string mTitle;
private int id = new Random().Next(0, 20);
[ResourceUri]
public string ResourceUri
{
get { return "This " + id.ToString(); }
}
[RdfProperty(false, Name="item")]
public Item[] Items;
}
Created this way:
var item = new AllItems();
item.mTitle = "Hello World!";
item.Items = new Item[] { new Item() { MyProp = "test1" }, new Item() { MyProp = "test2" } };
var doc = Rdfizer.Serialize(item);
System.Console.Out.Write(doc.ToString());
Here is a part of the result:
<ns:AllItems rdf:about="This 1">
<ns:mTitle rdf:datatype="http://www.w3.org/2001/XMLSchema#string
">Hello World!</ns:mTitle>
<ns:item>
<ns:Item>
<ns:MyProp rdf:datatype="http://www.w3.org/2001/
XMLSchema#string">test1</ns:MyProp>
</ns:Item>
</ns:item>
<ns:item>
<ns:Item>
<ns:MyProp rdf:datatype="http://www.w3.org/2001/
XMLSchema#string">test2</ns:MyProp>
</ns:Item>
</ns:item>
</ns:AllItems>
First question is: How could I make and be a single tag?
Second question: How could I make tag not visible, but only its content? i.e. all of its children to be direct children of tag.

In short: what you want violates RDF specs. It looks like you would like to treat the output as XML, but you shouldn't!
In RDF, you manipulate the triples and you should never ever care how it is serialized into XML, because RDF is syntax independent and RDF/XML serialization specs allows to represent the same set of triples many different way. To illustrate it, you might pick RDF Tool "A" create an RDF document. You pick RDF Tool "B", load that document and save it under a new name again without any modification. You compare the two files and you will find the same triples inside but the two XML files might look quite different! You cannot make tags come and go, actually tags are "not your business" :).
The bottomline is, if you want to dictate how your output XML should look like, you should just forget RDF completely and just use plain old XML tools to do get the job done.