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Can I get an explaination of this short code that generates a random string in unicode?

I'm currently in a c# class and wanted a full explaination of every line in this short code. I can see what happens in the form but I don't fully know how to explain it since some parts copied from the internet (new char[] for example) and how all of them work together. Thanks in advance would be a great help!
private void BtnSkapa_Click(object sender, EventArgs e)
{
int längd = int.Parse(tbxLängd.Text);
var lösen = new char[längd];
string tecken = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!#¤%&?<>£${[]}§+#£$";
Random random = new Random();
for (int i = 0; i < längd; i++)
{
lösen[i] = tecken[random.Next(tecken.Length)];
lblLösen.Text = new string(lösen);
}
}

For what it's worth, some comments on the code:
private void BtnSkapa_Click(object sender, EventArgs e)
{
int längd = int.Parse(tbxLängd.Text); // attempts to convert the String in (presumably) the TextBox "tbxLängd" to an integer
var lösen = new char[längd]; // creates an ARRAY of char, with length "längd"
string tecken = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!#¤%&?<>£${[]}§+#£$"; // "tecken" holds all the possible candidates to be chosen from
Random random = new Random(); // creates an instance of the Random class so we can generate a random number below
for (int i = 0; i < längd; i++) // setup a for loop that will iterate "längd" times
{
lösen[i] = tecken[random.Next(tecken.Length)]; // assign a random value from "tecken" to the current position in the "lösen" array
lblLösen.Text = new string(lösen); // creates a string from the character array (this could be put OUTSIDE the for loop down below)
}
}
Note that a character array is not necessarily required. You could create a blank string and concatenate the next random value to the end of that. There are many other ways to accomplish the same end goal...
Yeah I did that and believe I understand all except on why I need to use "new char[]"
In the code we are getting a random value from the source string with:
lösen[i] = tecken[random.Next(tecken.Length)];
This works because you can use an indexer to access any position in the string as a char. Since it returns a char, it makes sense to make an array of char.
Once the array is populated with chars, we create a string from that array by passing it to this string constructor.

Using another classes function in c#

im trying to be able to call the function from the dieclass and use the roll number in the matchplay class... is this possible?
public class DieClass
{
public void DiceRoll(int min, int max)
{
Random random = new Random();
int roll1 = random.Next(0, 6);
int roll2 = random.Next(0, 6);
int roll3 = random.Next(0, 6);
}
}
public class MatchPlay
{
public void Match()
{
DieClass.DiceRoll();
Console.WriteLine("Starting Match Play...");
Console.WriteLine();
Console.WriteLine("Round One");
Console.WriteLine("Your first dice is [0]", roll1);
Console.WriteLine("Your second dice is [0]", roll2);
Console.WriteLine("Your third dice is [0]", roll3);
}
}
}

There are a few things that need fixin':
Your DiceRoll method is an instance method, so you'd need to create an instance of the DiceClass class in order to use it.
The roll1, roll2, and roll3 variables are local to the method, so you won't be able to use them once the method completes. Instead, you might make them public properties of the class.
You don't need to instantiate a new Random every time the method is called (in fact this can lead to problems because Random is seeded with a value based on the system clock, so if your method is called very rapidly, it will produce the same numbers over and over). You can just make it static and instantiate it once.
Since you're taking in min and max arguments to the Roll method, shouldn't we use them? You currently have 0 and 6 hard-coded.
To use a format string, you need to use the curley braces ({}) instead of square brackets ([]).
Finally, from a naming convention point of view, you don't need the word Class as part of your class name, and you don't need Dice as part of the method name. This will simplify the amount of typing, and will still be very understandable.
What you might consider doing is creating a class that represents a single Die object, and give it a Roll() method and a Value property. Then the user can create as many as they like and keep them in a List:
public class Die
{
public int Value { get; set; }
// Make this static and instantiate it only once to avoid re-seeding issues
private static readonly Random rnd = new Random();
public Die()
{
Value = 1;
}
public void Roll()
{
// This method uses values 1-6 as a standard die
Roll(1, 6);
}
public void Roll(int minValue, int maxValue)
{
Value = rnd.Next(minValue, maxValue + 1);
}
}
Now, you can use the Die class as follows:
public class MatchPlay
{
public void Match()
{
// Add three Die objects to our list of dice
List<Die> dice = new List<Die>
{
new Die(), new Die(), new Die()
};
Console.WriteLine("Starting Match Play...");
Console.WriteLine();
Console.WriteLine("Round One");
// Roll all dice
dice.ForEach(d => d.Roll());
Console.WriteLine("Your first dice is {0}", dice[0].Value);
Console.WriteLine("Your second dice is {0}", dice[1].Value);
Console.WriteLine("Your third dice is {0}", dice[2].Value);
}
}
Finally, we can kick off a match in our Main method:
private static void Main()
{
MatchPlay game = new MatchPlay();
game.Match();
Console.WriteLine("\nDone!\nPress any key to exit...");
Console.ReadKey();
}

Either you need to make DiceRoll a static method, or create an instance of DieClass and call your method through that.
For example, you may declare your method as
public static void DiceRoll(int min, int max)
Or you can instantiate an object like:
DieClass dice = new DieClass();
dice.DiceRoll(0, 6);
That being said, you have other problems with your DieClass class, the most obvious of which is you need a means of communicating the result back to the caller. The easiest approach would be to have DiceRoll() generate a single result and return that. Also, you've hardcoded 0 and 6 as your params to random.Next() despite the method expecting a pair of parameters min and max.

random number in constructor c#

I am a student taking an introductory programming course in line with game development. One of my assignments calls for me to define a players attack damage inside of the constructor. I want the damage to be random, but no matter what I do I get back the same number. This is a test I made to see how I can get this number to be random.
class MainChar
{
public static Random random = new Random();
public int Atk;
public MainChar()
{
this.Atk = random.Next(11);
}
public void h()
{
while (Atk != 10)
{
Console.WriteLine(Atk);
}
}
}
I'm creating a new instance of MainChar in my main program, and running h(). I get a repeating list of the same number instead of random numbers between 1 and 10. Any ideas?
P.S. This thread was useful, but could not answer my question.

In the method h(), the while forms an infinite loop if the atk!=10. so you need to specify an exit condition there to break the loop; you can use like this:
public void h()
{
while (Atk != 10)
{
this.Atk = random.Next(11);
}
Console.WriteLine(Atk);
}
Now you will get a random number between 0 and 11 and is not 10 in the console

if you want to continue with a random number until it generate a breaking condition or number, you can modify the h() func as:
public int Atk;
public static int max = 100;
public void h()
{
while (Atk != 10)
{
this. Atk = random.Next(max);
Console.WriteLine(Atk);
}
}

Only put random number in list if doesn't exist in a different list

I have another list named lRVars
I am trying to generate another list with a hashSet generated from a loop as follows, however, I need to make sure that the number doesn't already exist in the above list:
List<int> lCVars = new List<int>();
HashSet<int> hCVars = new HashSet<int>();
while (hCVars.Count < randCVarsCount)
{
hCVars.Add(rnd.Next(1, 11));
}
lColVars = hsColVars.ToList();
So in the above loop, I need to check if the rnd.Next already exists in the list being compared and can't figure out the syntax.
An extra eye would be great.

You just need a temporary variable for the random number and use that to check it already exists.
You could add an else clause and only add it to the HashSet if it isn't already in there, but the Add method does that (i.e. hs.Add(8); hs.Add(8); //hs will only have count of 1)
List<int> lCVars = new List<int>();
HashSet<int> hCVars = new HashSet<int>();
var rnd = new Random();
var randCVarsCount = 5;
while (hCVars.Count < randCVarsCount)
{
var num = rnd.Next(1, 11);
if (hCVars.Contains(num))
Console.WriteLine("already in there");
hCVars.Add(num);
}
lColVars = hsColVars.ToList();

Since the HashSet.ToList() method returns a new List, converting the HashSet into a List should guarantee the uniqueness of the values within your List object.
The source code for the ToList method showing this is below:
public static List<TSource> ToList<TSource> (this IEnumerable<TSource> source)
{
Check.Source (source);
return new List<TSource> (source);
}
In your app, you just need your own temporary variable to store the random number you wish to check. The sample program below shows the two ways of doing it.
#define UNCONDITIONAL
using System;
using System.Collections.Generic;
using System.Linq;
namespace StackOverflow
{
class MainClass
{
public static void Main (string[] args)
{
HashSet<int> hash = new HashSet<int>();
Random rnd = new Random();
#if(UNCONDITIONAL)
Console.WriteLine("Adding unconditionally...");
#else
Console.WriteLine("Adding after checks...");
#endif
while(hash.Count < 5)
{
int rv = rnd.Next (1, 11);
#if(UNCONDITIONAL)
hash.Add (rv);
#else
if(hash.Contains(rv))
{
Console.WriteLine ("Duplicate skipped");
}
else
{
hash.Add (rv);
}
#endif
}
List<int> list = hash.ToList (); // ToList() gives back a new instance
foreach(var e in list)
{
Console.WriteLine (e);
}
}
}
}
NOTE: The UNCONDITIONAL symbol is simply to let you play around with an example more easily. You can comment it out to see both behaviors.
Sample output with symbol defined:
Adding unconditionally...
5
10
2
6
3
Sample output with symbol commented out:
Adding after checks...
Duplicate skipped
7
3
4
2
10

Random not working

To clarify, multiple students objects and all of them are getting the same value.
I know this question has been asked before, but I have had no luck with the other posts about his topic. I have a random number generator ranging from 1-3. I then us %2 to make a bool value true or false. Every time I run the program I either get all true or all false. Here is my code. I know that random is not really random. What can I do to get more random numbers.
Random random = new Random();
public Student()
{
int randomLevel=random.Next(1,3);
level = (randomLevel % 2 == 0);
}
public bool readingLevel()//this always returns one value for the entire program.
{
return level;
}

You are only assigning a random value to 'level' once during the constructor, so it will always have the initial value.
Try:
public bool readingLevel()
{
return (random.Next(1,3) % 2 == 0);
}
Edit:
Static Random random = new Random();
...

It looks like you're trying to get a random number!
Clippy
Well you can try something like this:
static Random random = new Random();
public Student()
{
lock (random)
{
int randomLevel=random.Next(1,3);
level = (randomLevel % 2 == 0);
}
}
public bool readingLevel()//this always returns one value for the entire program.
{
return level;
}
The problem with your snippet seems to be that you are instantiating a new Random class with each of your class instances.
This is not the way Random is supposed to be used, but instead a single Random class instance should be used for acquiring multiple random numbers.
The Rationale for this is that Random in .Net uses a pseudo random algorithm based on state (a seed) that changes every time you ask for a new random number. By instantiating multiple random classes in a relatively short time span, there is a high chance that all of them will be initiated with the same seed (Based on system time) and all will give the same random number.

It looks like your random generator is an instance variable of the Student. Since the generator uses the current time as the seed, if you create a bunch of students within a short time, they will all have each have a generator with the same seed and the same results. You could make the random generator a static variable or, better yet, use constructor injection and pass the level into the Student's constructor.
class Student
{
private static Random random = new Random();
public Student()
{
level = random.NextDouble() < 0.5;
}
public bool readingLevel()
{
return level;
}
}
or use constructor injection so your student class is deterministic.
class Student
{
private boolean level;
public Student(boolean readingLevel)
{
this.level = readingLevel;
}
public boolean readingLevel()
{
return level;
}
}

Create only one instance of Random and reuse it. Creating multiple instances of random in quick succession seeds to the same value and thus leads to the same sequence.
If your code in single threaded you can simply use a static property to hold the instance of Random.
The default seed value is derived from the system clock and has finite resolution. As a result, different Random objects that are created in close succession by a call to the default constructor will have identical default seed values and, therefore, will produce identical sets of random numbers. This problem can be avoided by using a single Random object to generate all random numbers. You can also work around it by modifying the seed value returned by the system clock and then explicitly providing this new seed value to the Random(Int32) constructor. For more information, see the Random(Int32) constructor.
http://msdn.microsoft.com/en-us/library/h343ddh9.aspx

public Student()
{
int randomLevel=random.Next(1,3);
level = (randomLevel % 2 == 0);
}
seems very much like a constructor for the Student class. In this constructor you are basically calculating a random number and storing it inside the level field. So if you use the same instance of Student throughout your entire program and call the readingLevel() method multiple times on this instance it will obviously return the same value -> the one that was done during the construction of this instance and that you stored in the level field.
So you might consider moving the random number generation logic into the readingLevel() method instead of simply returning the same value over and over again:
public class Student
{
private Random random = new Random();
public bool readingLevel()
{
int randomLevel = random.Next(1,3);
return (randomLevel % 2 == 0);
}
}
Now everytime you call this method on the same instance you should get a new calculation of a random number.

Some others have said this, but I think the point deserves underscoring with an example.
public class Student
{
Random random = new Random();
public Student()
{
int randomLevel=random.Next(1,3);
level = (randomLevel % 2 == 0);
}
public bool readingLevel()//this always returns one value for the entire program.
{
return level;
}
}
public class Program
{
public static void Main()
{
var students = new List<Student>();
for (int i = 0; i < 10; i++)
students.Add(new Student());
//Now you have 10 Students; each Student has its own random number generator
//The generators were created within microseconds of each other, so they most likely have THE SAME SEED
//Because they have the same seed, they will generate identical sequences of numbers
//Each student's reading level is calculated from the first call to .Next(1, 3) on its own RNG.
//The RNGs have the same seed, so each will return the same value for the first call to .Next(1, 3)
//Therefore, all students will have the same reading level!
}
}

You are using random to simulate a true/false situation, so you are trying to limit the result to either 1 or 2. Given that you are doing an odd/even test on the result you might be better off doing:
int randomLevel = random.Next();
level = (randomLevel % 2 == 0);
Also If you create all your students in quick succession there's a good chance that your current code will return the same value for subsequent calls.

Well.
Consider what is happening here. When your Student is constructued, you get some random number, and then set it to the member variable level.
Then, at some other point, you call a function, readingLevel, which returns this previously set value.
Then, you may ponder to yourself: Exactly when would this function give a different value? Well, it will only do so when level gets a different value. And when does that happen? Well, it only happens in the constructor, so, that means, it never happens again for the life of the object ....

Try the following. Move the selection of the random level to the readingLevel function.
Random random = new Random();
public Student()
{
}
public bool readingLevel()//this always returns one value for the entire program.
{
int randomLevel=random.Next(1,3);
level = (randomLevel % 2 == 0);
return level;
}

That is because you are using the random.Next() and the level evaluation within the constructor of your class, remember that the constructor is only executed when you create a new instance of your object, for having it executed several times create a different method where you call the random and the level evaluation, that way you'll get different values every time or use Something like this:
public bool Level()
{
int randomLevel=random.Next(1,3);
level = (randomLevel % 2 == 0);
return level;
}

Random random = new Random(DateTime.Now.Ticks);