I have been practicing c# nowadays and decided to write a code that converts any decimal to any base representation for practice purpose. And i have some troubles. Since i want to practice i decided to do it with an additional function where calculations take place. First i wanted to use an array to keep my result. But since ,at the beginning, i do not know the length of the array i could not define it.So i decided to use list(somehow i assumed undeclared slots are 0 as default). This is what i end up with.
class MainClass
{
static double number;
static double baseToConvert;
static int counter = 0;
static List<double> converted = new List<double>();
public static void Main(string[] args)
{
Console.WriteLine("Enter a decimal");
number = double.Parse(Console.ReadLine());
Console.WriteLine("Enter a base you want to convert to");
baseToConvert = double.Parse(Console.ReadLine());
ConverterToBase(number);
for (int i = converted.Count - 1; i >= 0; i--)
{
Console.WriteLine(converted[i]);
}
Console.ReadLine();
}
public static void ConverterToBase(double x)
{
double temp = x;
while (x >= baseToConvert)
{
x /= baseToConvert;
counter++;
}
converted[counter] = x;
counter = 0;
if (temp - x * Math.Pow(baseToConvert, Convert.ToDouble(counter)) >= baseToConvert)
{
ConverterToBase(temp - x * Math.Pow(baseToConvert, Convert.ToDouble(counter)));
}
else
{
converted[0] = temp - x * Math.Pow(baseToConvert, Convert.ToDouble(counter));
}
}
}
But after i write inputs console gets stuck without an error. My guess is that since i do not have any elements in the list " converted[counter] " does not make sense. But i do not know maybe the problem is somewhere else.
My question is not about the way i calculate the problem(Of course any suggestions are welcomed). I just want to know what i am doing wrong and how i can handle such situation(unknown array size , use of list , accessing a variable,array,.. etc from another method... ).
Thanks.
My previous answer was wrong as pointed out by #Rufus L. There is no infinite for loop. However upon further review, there seems to be an infinite recursion going on in your code in this line:
if (temp - x * Math.Pow(baseToConvert, Convert.ToDouble(counter)) >= baseToConvert)
{
ConverterToBase(temp - x * Math.Pow(baseToConvert, Convert.ToDouble(counter)));
}
ConverterToBase calls itself and there seems to be no base case nor return statement to end the recursion.
In the method named "ConverterToBase(double x)" you want to set value of 0 element. But you didn't add any element. The converted is Empty.
Firstly add value or values to your list.
Related
I've been working on a project where I need on a button press that this line gets executed.
if (listView1.SelectedItems[0].SubItems[3].Text == "0") //Checks to see Value
{
listView1.SelectedItems[0].SubItems[3].Text = "1";// If Value is Greater, Increase and Change ListView
questionNumberLabel.Text = listView1.SelectedItems[0].SubItems[3].Text;// Increase and Change Label
}
Now I have this repeated about 10 times with each value increasing by one. But I know that this is ugly, and dysfunctional. As well as conflates the file size. I've tried a few things. Primarily this method.
if (listView1.SelectedItems[0].SubItems[3].Text == "0")
{
for (var i = 1; i < 100;)
{
if (!Int32.TryParse(listView1.SelectedItems[0].SubItems[3].Text, out i))
{
i = 0;
}
i++;
listView1.SelectedItems[0].SubItems[3].Text = i.ToString();
Console.WriteLine(i);
}
}
But instead of just adding one, it does the 100 instances and ends. The reason this is becoming a pain in the *** is because the
listView1.SelectedItems[0].SubItems[3].Text
is just that - it's a string, not an int. That's why I parsed it and tried to run it like that. But it still isn't having the out come I want.
I've also tried this
string listViewItemToChange = listView1.SelectedItems[0].SubItems[3].Text;
Then parsing the string, to make it prettier. It worked like it did before, but still hasn't given me the outcome I want. Which to reiterate is, I'm wanting the String taken from the list view to be changed into an int, used in the for loop, add 1, then restring it and output it on my listView.
Please help :(
You say you want the text from a listview subitem converted to an int which is then used in a loop
so - first your creating your loop variable, i, then in your loop you're assigning to it potentially 3 different values 2 of which are negated by the, i++. None of it makes sense and you shouldn't be manipulating your loop variable like that (unless understand what you're doing).
if you move statements around a little..
int itemsToCheck = 10; // "Now I have this repeated about 10 times "
for (var item = 0; item < itemsToCheck; item++)
{
int i;
if (!Int32.TryParse(listView1.SelectedItems[item].SubItems[3].Text, out i))
{
i = 0;
}
i++;
listView1.SelectedItems[item].SubItems[3].Text = i.ToString();
Console.WriteLine(i);
}
Something along those lines is what you're looking for. I haven't changed what your code does with i, just added a loop count itemsToCheck and used a different loop variable so your loop variable and parsed value are not one in the same which will likely be buggy.
Maybe this give you an idea. You can start using this syntax from C# 7.0
var s = listView1.SelectedItems[0].SubItems[3].Text;
var isNumeric = int.TryParse(s, out int n);
if(isNumeric is true && n > 0){
questionNumberLabel.Text = s;
}
to shortcut more
var s = listView1.SelectedItems[0].SubItems[3].Text;
if(int.TryParse(s, out int n) && n > 0){
questionNumberLabel.Text = s;
}
I am creating a Dungeons and Dragons Character Creator. There is a randomize feature that is going to create a complete character sheet. There is a part that I have gotten to and I am not quite sure the best way to proceed.
The way I have the racial modifiers set up is with if statements. Here is an example.
if (raceInt == 0 || raceInt == 2 || raceInt == 10)
{
raceStrMod = 2;
}
if (raceInt == 3 || raceInt == 4 || raceInt == 5 || raceInt == 11 || raceInt == 12)
{
raceDexMod = 2;
}
However there are races that have modifiers that let you select two stats to add a modifier to, such as Strength or Dexterity. What would be the best way to select two random ints for just those races?
For example, the half-elf race which would get +2 to Dex and then +1 to two other random stats. So I need to find a way to randomly select two of the remaining ints to make the value = 1.
My race mod ints are initialized as
int raceStrMod = 0;
int raceDexMod = 0;
int raceConMod = 0;
int raceIntMod = 0;
int raceWisMod = 0;
int raceChaMod = 0;
Then the if statements assign a value dependent on which race was randomly selected.
Thank you all for the input! This is how I ended up coding it
if (raceInt == 9)
{
int randomX = rnd.Next(1, 5);
int randomY = rnd.Next(1, 5);
int attempts = 0;
while (randomX == randomY && attempts < 10)
{
randomY = rnd.Next(1, 5);
attempts++;
}
//if they are still not unique after 10 attempts
if (randomX == randomY)
{
if (randomX == 5)
randomY = 1;
else
randomY = randomX + 1;
}
int[] randomNumbers = { randomX, randomY };
foreach (int i in randomNumbers)
{
switch (i)
{
case 1:
raceStrMod = 1;
break;
case 2:
raceDexMod = 1;
break;
case 3:
raceConMod = 1;
break;
case 4:
raceIntMod = 1;
break;
case 5:
raceWisMod = 1;
break;
}
}
}
Has your class introduced you to enum types yet? If not, is there any restriction on your final project with respect to using language features that weren't taught in the class?
Your question is arguably too broad, as there are many different ways to address this sort of thing even in real-world code, and the classroom context introduces potential roadblocks that while might constrain the question, being unknown they make it impossible to know what answer is actually going to work for you.
That said…
Ignoring the classroom aspect and focusing only on the problem itself, I would use enum types and dictionaries for this sort of thing. For example:
enum Attribute
{
Strength,
Dexterity,
Constitution,
Charisma,
Intelligence,
Wisdom,
Count, // must always be last
}
Dictionary<Attribute, int> modifiers = new Dictionary<Attribute, int>();
Then you can pick a random attribute like (assuming you have a random variable referencing a Random object…don't make the classic newbie mistake of creating a new Random object every time you want to pick a new random number):
Attribute attributeToModify = (Attribute)random.Next((int)Attribute.Count);
And you can store that selection like:
modifiers[attributeToModify] = 1;
This can be used to store however many modifiers you like. You can encapsulate that in an object representing the character itself, or you could put it into a separate AttributeModifiers class. One advantage of doing the latter would be that if you have modifiers that come from different sources, you can track that in the character object as a list of AttributeModifier instances, each in turn keeping track of what the actual source of those modifiers are.
This just barely scratches the surface. As I noted, the question itself is fairly broad. But I strongly recommend using the available language features to ensure that your variables represent things in a type-specific way, rather than just using int values for things that aren't really integers, and to use collection classes that more correctly represent the semantics of what your code is intended to do.
Note that this also means you probably should have an enum type for the races. E.g.:
enum Race
{
Dwarf,
Elf,
HalfElf,
Halfling,
HalfOrc,
Human,
// etc.
}
And your chain of if statements is probably better represented as a switch:
Attribute racialMod;
switch (race)
{
case Human:
case Halfling:
// etc.
racialMod = Attribute.Strength;
break;
case Elf:
case HalfElf:
// etc.
racialMod = Attribute.Dexterity;
break;
}
modifiers[racialMod] = 2;
Something like that. The point is to make sure the code reads more like what the original specification would say (if you actually had written one). This will make the code easier to understand, and it will be less likely for you to put bugs in the code (e.g. you accidentally type the wrong magic, unnamed integer).
I am creating a Dungeons and Dragons Character Creator.
That's a fun beginner project; I did the same when I was learning to program.
I need to find a way to randomly select two of the remaining...
You need to find two distinct values, call then x and y. The solution you've arrived at is:
Generate x
Try to generate y ten times
If no attempt succeeded to find a distinct y, hard-code a choice.
That works, and you almost never have to use the hard-coded choice. But I thought you might be interested to know that there is an easier way to generate two distinct numbers. Let's suppose we want two distinct numbers from 0, 1, 2, 3 or 4. (Obviously if you want a different range, say, 1 through 5, you can solve that problem by generating two distinct numbers 0->4 and then adding one to each.)
The improved algorithm is:
Choose x between 0 and 4 as usual.
Choose n between 1 and 4.
y = (x + n) % 5;
Think about it this way. Suppose we make a list like this:
0, 1, 2, 3, 4, 0, 1, 2, 3
We randomly choose x from the first five entries on the list, and then we choose y by stepping forwards between 1 and 4 steps. Since the list does not repeat in one to four steps, we know that we'll get two unique elements. The math does the equivalent of that.
You could similarly have used % in your program:
if (randomX == 5)
randomY = 1;
else
randomY = randomX + 1;
could be written
randomY = randomX % 5 + 1
If you're unfamiliar with %, it is the remainder operator. It is the complement of the / operator. The rule is:
int x = whatever;
int y = whatever;
int r = x % y;
is the same as:
int r = x - (x / y) * y;
That is, it is the remainder when x is divided by y. Keep in mind that the remainder can be negative!
(Disclaimer: I don't love this option, but couldn't think of another way other than reflection which is even nastier)
You could define a class that masks the fact that all of the mods are stored as an array and therefore can be indexed using a random number.
Something like the following:
public class StatMods
{
public int RaceStrMod { get { return this.mods[0]; } set { this.mods[0] = value; } }
public int RaceDexMod { get { return this.mods[1]; } set { this.mods[1] = value; } }
public int RaceConMod { get { return this.mods[2]; } set { this.mods[2] = value; } }
public int RaceIntMod { get { return this.mods[3]; } set { this.mods[3] = value; } }
public int RaceWisMod { get { return this.mods[4]; } set { this.mods[4] = value; } }
public int RaceChaMod { get { return this.mods[5]; } set { this.mods[5] = value; } }
private readonly int[] mods;
private static readonly Random rand = new Random();
public StatMods()
{
this.mods = new int[6];
}
public void ApplyRandomMod(int modification)
{
this.mods[rand.Next(0, 6)] += modification;
}
}
I have been programming an object to calculate the DiceSorensen Distance between two strings. The logic of the operation is not so difficult. You calculate how many two letter pairs exist in a string, compare it with a second string and then perform this equation
2(x intersect y)/ (|x| . |y|)
where |x| and |y| is the number of bigram elements in x & y. Reference can be found here for further clarity https://en.wikipedia.org/wiki/S%C3%B8rensen%E2%80%93Dice_coefficient
So I have tried looking up how to do the code online in various spots but every method I have come across uses the 'Intersect' method between two lists and as far as I am aware this won't work because if you have a string where the bigram already exists it won't add another one. For example if I had a string
'aaaa'
I would like there to be 3 'aa' bigrams but the Intersect method will only produce one, if i am incorrect on this assumption please tell me cause i wondered why so many people used the intersect method. My assumption is based on the MSDN website https://msdn.microsoft.com/en-us/library/bb460136(v=vs.90).aspx
So here is the code I have made
public static double SorensenDiceDistance(this string source, string target)
{
// formula 2|X intersection Y|
// --------------------
// |X| + |Y|
//create variables needed
List<string> bigrams_source = new List<string>();
List<string> bigrams_target = new List<string>();
int source_length;
int target_length;
double intersect_count = 0;
double result = 0;
Console.WriteLine("DEBUG: string length source is " + source.Length);
//base case
if (source.Length == 0 || target.Length == 0)
{
return 0;
}
//extract bigrams from string 1
bigrams_source = source.ListBiGrams();
//extract bigrams from string 2
bigrams_target = target.ListBiGrams();
source_length = bigrams_source.Count();
target_length = bigrams_target.Count();
Console.WriteLine("DEBUG: bigram counts are source: " + source_length + " . target length : " + target_length);
//now we have two sets of bigrams compare them in a non distinct loop
for (int i = 0; i < bigrams_source.Count(); i++)
{
for (int y = 0; y < bigrams_target.Count(); y++)
{
if (bigrams_source.ElementAt(i) == bigrams_target.ElementAt(y))
{
intersect_count++;
//Console.WriteLine("intersect count is :" + intersect_count);
}
}
}
Console.WriteLine("intersect line value : " + intersect_count);
result = (2 * intersect_count) / (source_length + target_length);
if (result < 0)
{
result = Math.Abs(result);
}
return result;
}
In the code somewhere you can see I call a method called listBiGrams and this is how it looks
public static List<string> ListBiGrams(this string source)
{
return ListNGrams(source, 2);
}
public static List<string> ListTriGrams(this string source)
{
return ListNGrams(source, 3);
}
public static List<string> ListNGrams(this string source, int n)
{
List<string> nGrams = new List<string>();
if (n > source.Length)
{
return null;
}
else if (n == source.Length)
{
nGrams.Add(source);
return nGrams;
}
else
{
for (int i = 0; i < source.Length - n; i++)
{
nGrams.Add(source.Substring(i, n));
}
return nGrams;
}
}
So my understanding of the code step by step is
1) pass in strings
2) 0 length check
3) create list and pass up bigrams into them
4) get the lengths of each bigram list
5) nested loop to check in source position[i] against every bigram in target string and then increment i until no more source list to check against
6) perform equation mentioned above taken from wikipedia
7) if result is negative Math.Abs it to return a positive result (however i know the result should be between 0 and 1 already this is what keyed me into knowing i was doing something wrong)
the source string i used is source = "this is not a correct string" and the target string was, target = "this is a correct string"
the result I got was -0.090909090908
I'm SURE (99%) that what I'm missing is something small like a mis-calculated length somewhere or a count mis-count. If anyone could point out what i'm doing wrong I'd be really grateful. Thank you for your time!
This looks like homework, yet this similarity metric on strings is new to me so I took a look.
Algorith implementation in various languages
As you may notice the C# version uses HashSet and takes advantage of the IntersectWith method.
A set is a collection that contains no duplicate elements, and whose
elements are in no particular order.
This solves your string 'aaaa' puzzle. Only one bigram there.
My naive implementation on Rextester
If you prefer Linq then I'd suggest Enumerable.Distinct, Enumerable.Union and Enumerable.Intersect. These should mimic very well the duplicate removal capabilities of the HashSet.
Also found this nice StringMetric framework written in Scala.
This is a formula to approximate arcsine(x) using Taylor series from this blog
This is my implementation in C#, I don't know where is the wrong place, the code give wrong result when running:
When i = 0, the division will be 1/x. So I assign temp = 1/x at startup. For each iteration, I change "temp" after "i".
I use a continual loop until the two next value is very "near" together. When the delta of two next number is very small, I will return the value.
My test case:
Input is x =1, so excected arcsin(X) will be arcsin (1) = PI/2 = 1.57079633 rad.
class Arc{
static double abs(double x)
{
return x >= 0 ? x : -x;
}
static double pow(double mu, long n)
{
double kq = mu;
for(long i = 2; i<= n; i++)
{
kq *= mu;
}
return kq;
}
static long fact(long n)
{
long gt = 1;
for (long i = 2; i <= n; i++) {
gt *= i;
}
return gt;
}
#region arcsin
static double arcsinX(double x) {
int i = 0;
double temp = 0;
while (true)
{
//i++;
var iFactSquare = fact(i) * fact(i);
var tempNew = (double)fact(2 * i) / (pow(4, i) * iFactSquare * (2*i+1)) * pow(x, 2 * i + 1) ;
if (abs(tempNew - temp) < 0.00000001)
{
return tempNew;
}
temp = tempNew;
i++;
}
}
public static void Main(){
Console.WriteLine(arcsin());
Console.ReadLine();
}
}
In many series evaluations, it is often convenient to use the quotient between terms to update the term. The quotient here is
(2n)!*x^(2n+1) 4^(n-1)*((n-1)!)^2*(2n-1)
a[n]/a[n-1] = ------------------- * --------------------- -------
(4^n*(n!)^2*(2n+1)) (2n-2)!*x^(2n-1)
=(2n(2n-1)²x²)/(4n²(2n+1))
= ((2n-1)²x²)/(2n(2n+1))
Thus a loop to compute the series value is
sum = 1;
term = 1;
n=1;
while(1 != 1+term) {
term *= (n-0.5)*(n-0.5)*x*x/(n*(n+0.5));
sum += term;
n += 1;
}
return x*sum;
The convergence is only guaranteed for abs(x)<1, for the evaluation at x=1 you have to employ angle halving, which in general is a good idea to speed up convergence.
You are saving two different temp values (temp and tempNew) to check whether or not continuing computation is irrelevant. This is good, except that you are not saving the sum of these two values.
This is a summation. You need to add every new calculated value to the total. You are only keeping track of the most recently calculated value. You can only ever return the last calculated value of the series. So you will always get an extremely small number as your result. Turn this into a summation and the problem should go away.
NOTE: I've made this a community wiki answer because I was hardly the first person to think of this (just the first to put it down in a comment). If you feel that more needs to be added to make the answer complete, just edit it in!
The general suspicion is that this is down to Integer Overflow, namely one of your values (probably the return of fact() or iFactSquare()) is getting too big for the type you have chosen. It's going to negative because you are using signed types — when it gets to too large a positive number, it loops back into the negative.
Try tracking how large n gets during your calculation, and figure out how big a number it would give you if you ran that number through your fact, pow and iFactSquare functions. If it's bigger than the Maximum long value in 64-bit like we think (assuming you're using 64-bit, it'll be a lot smaller for 32-bit), then try using a double instead.
I'm running this class and method
public class DiceRoll
{
static Random _r =new Random();
public int Random6()
{
int n = _r.Next(1, 7);
return n;
}
}
I'm trying to use it inside an if statement in another class like so:
if (input == "d6")
{
int dice = diceRoll.Random6();
Console.WriteLine(dice);
}
my question is this. If I call diceRoll.Random6(); with a multiplier like this diceRoll.Random6() * 2; Is it creating two random numbers and adding them or is it just taking one and multiplying it by two?
I think it's probably the latter but I just wanted to check before I got into convoluted programming.
If it is the latter is there a way to make my program call multiple instances of Random6 without going diceRoll.Random6() + diceRoll.Random6(); That works ok for doing it twice but if I want to do it four or six times it'll become inelegant.
Thanks in advance.
Call the method from within a loop
int result = 0;
for(int i = 0; i < 10; i++)
{
result += Random6();
}
It just generates 1 random number then multiplies it by 2
you can just do it in a loop, or if you want to be fancy
var sum = Enumerable.Range(1, 6).Sum(x => diceRoll.Random6())
which you might want to break down into...
var rolls = Enumerable.Range(1, 6).Select(x => diceRoll.Random6()).ToList();
var sumOfRolls = rolls.Sum();
that way you have the sum and a list of each individual roll.