Develop Reference

What is stopping this program from having an output

I made this code to brute force anagrams by printing all possible permutables of the characters in a string, however there is no output. I do not need simplifications as I am a student still learning the basics, I just need help getting it to work this way so I can better understand it.
using System;
using System.Collections.Generic;
namespace anagramSolver
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Enter anagram:");
string anagram = Console.ReadLine();
string temp = "";
List<string> storeStr = new List<string>(0);
List<int> storeInt = new List<int>(0);
//creates factorial number for anagram
int factorial = 1;
for (int i = anagram.Length; i > 0; i--)
{
factorial *= i;
}
while (storeStr.Count != factorial)
{
Random rnd = new Random();
while(temp.Length != anagram.Length)
{
int num = rnd.Next(anagram.Length - 1);
if (storeInt.Contains(num) == true)
{
}
else
{
storeInt.Add(num);
temp += anagram[num];
}
}
if (storeStr.Contains(temp) == true)
{
temp = "";
}
else
{
storeStr.Add(temp);
Console.WriteLine(temp, storeStr.Count);
temp = "";
}
}
}
}
}
edit: added temp reset after it is deemed contained by storeStr

Two main issues causing infinite loop:
1)
As per Random.Next documentation, the parameter is the "exclusive" upper bound. This means, if you want a random number between 0 and anagram.Length - 1 included, you should use rnd.Next(anagram.Length);.
With rnd.Next(anagram.Length - 1), you'll never hit anagram.Length - 1.
2)
Even if you solve 1, only the first main iteration goes well.
storeInt is never reset. Meaning, after the first main iteration, it will have already all the numbers in it.
So, during the second iteration, you will always hit the case if (storeInt.Contains(num) == true), which does nothing and the inner loop will go on forever.

Several issues here...
The expression rnd.Next(anagram.Length - 1) generates a value between 0 and anagram.Length - 2. For an input with two characters it will always return 0, so you'll never actually generate a full string. Remove the - 1 from it and you'll be fine.
Next, you're using a list to keep track of the character indices you've used already, but you never clear the list. You'll get one output (eventually, when the random number generator covers all the values) and then enter an infinite loop on the next generation pass. Clear storeInt after the generation loop to fix this.
While not a true infinite loop, creating a new instance of the random number generator each time will give you a lot of duplication. new Random() uses the current time as a seed value and you could potentially get through a ton of loops with each seed, generating exactly the same values until the time changes enough to change your random sequence. Create the random number generator once before you start your main loop.
And finally, your code doesn't handle repeated input letters. If the input is "aa" then there is only a single distinct output, but your code won't stop until it gets two. If the input was "aab" there are three distinct permutations ("aab", "aba", "baa") which is half of the expected results. You'll never reach your exit condition in this case. You could do it by keeping track of the indices you've used instead of the generated strings, it just makes it a bit more complex.
There are a few ways to generate permutations that are less error-prone. In general you should try to avoid "keep generating random garbage until I find the result I'm looking for" solutions. Think about how you personally would go about writing down the full list of permutations for 3, 4 or 5 inputs. What steps would you take? Think about how that would work in a computer program.

this loop
while(temp.Length != anagram.Length)
{
int num = rnd.Next(anagram.Length - 1);
if (storeInt.Contains(num) == true)
{
}
else
{
storeInt.Add(num);
temp += anagram[num];
}
}
gets stuck.
once the number is in storeInt you never change storeStr, yet thats what you are testing for loop exit

How to make this code more functional or 'prettier'

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;
}

Incremental counting and saving all values in one string

I'm having trouble thinking of a logical way to achieve this. I have a method which sends a web request with a for loop that is counting up from 1 to x, the request counts up until it finds a specific response and then sends the URL + number to another method.
After this, saying we got the number 5, I need to create a string which displays as "1,2,3,4,5" but cannot seem to find a way to create the entire string, everything I try is simply replacing the string and only keeping the last number.
string unionMod = string.Empty;
for (int i = 1; i <= count; i++)
{
unionMod =+ count + ",";
}
I assumed I'd be able to simply add each value onto the end of the string but the output is just "5," with it being the last number. I have looked around but I can't seem to even think of what I would search in order to get the answer, I have a hard-coded solution but ideally, I'd like to not have a 30+ string with each possible value and just have it created when needed.
Any pointers?
P.S: Any coding examples are appreciated but I've probably just forgotten something obvious so any directions you can give are much appreciated, I should sleep but I'm on one of those all-night coding grinds.
Thank you!

First of all your problem is the +=. You should avoid concatenating strings because it allocates a new string. Instead you should use a StringBuilder.
Your Example: https://dotnetfiddle.net/Widget/qQIqWx
My Example: https://dotnetfiddle.net/Widget/sx7cxq
public static void Main()
{
var counter = 5;
var sb = new StringBuilder();
for(var i = 1; i <= counter; ++i) {
sb.Append(i);
if (i != counter) {
sb.Append(",");
}
}
Console.WriteLine(sb);
}

As it's been pointed out, you should use += instead of =+. The latter means "take count and append a comma to it", which is the incorrect result you experienced.
You could also simplify your code like this:
int count = 10;
string unionMod = String.Join(",", Enumerable.Range(1, count));
Enumerable.Range generates a sequence of integers between its two parameters and String.Join joins them up with the given separator character.

IndexOutOfRange Exception Thrown on Setting Int value to Array

On my app a teacher can have several classes, and when I exclude a teacher's profile I have to, first, delete his classes. I'm trying to put each class_id of this teacher on an int array, to later delete all classes which the id is contained inside this array.
This is my code so far:
int x = 0;
int[] count = new int[x];
while (reader_SelectedClasses.Read())
{
if(x != 0)
{
x++;
count = new int[x];
}
count[x] = _class.Class_id = reader_SelectedClasses.GetInt16("class_id");
}
And this is what
reader_SelectedClasses.Read()
does:
select class_id from tbl_class where user_id = " + id + ";
And this is the return, when I try this on MySQL:
But it gives me back an IndexOutOfRangeException when I run the code on my DAO class. What am I missing? Already went here but didn't quite understand. Can someone please explain on few words and post and fixed code for this?

You need to learn how to use a debugger and step through your program.
count = new int[x]; discards what was in count and creates a new array that contains zeroes. This array's indexes go from 0 to x - 1.
count[x] = ... sets the array element at index x which according to the previous line is one past the end of the array.
You need to set count = new int[x] only once, at the beginning of your program, and set count[x] = ... only if x >= 0 and x < count.Length.

You are getting IndexOutOfRange Exception because you are trying to access element from array which is out of range.
At first line you are setting x = 1. Hoping that controller enters while loop and as x is 1 it doesn't enter if loop and it executes next statement. But count[1] (x = 1) is not allowed as you have created array with only one element and that you can access with count[0]. (Array indexing starts from 0)

You are trying to achieve a List behavior with an array.
Obviously, the IndexOutOfRangeException is because you initialize an empty array and then try to add values to it in a non-existing cell.
Try to convert to List<int>:
List<int> count = new List<int>();
while (reader_SelectedClasses.Read())
{
int classId = _class.Class_id = reader_SelectedClasses.GetInt16("class_id");
count.Add(classId);
}
If you really need an array out of it you can do:
int[] countArray = count.ToArray()

While Looping an Array

I'm trying to understand a book from Don Gosselin on ASP.NET Programming with Visual C#. To solve it I just simply make it to work by adhering to while loops: one while loop is to assign a number to an array element, the other while loop is to display that array. Total array count displays 1 through 100. This should have worked but didn't. Visual Studio 2013 debugger for some reason assigns count = 100, that's why it's failing.
<%
int count = 0;
int[] numbers = new int[100];
while (count <= 100)
{
numbers[count] = count;
++count;
}
while (count <= 100)
{
Response.Write(numbers[count] + "<br />");
++count;
}
%>

You should set count to 0 after first while loop:
int count = 0;
int[] numbers = new int[100];
while (count <= 100)
{
numbers[count] = count;
++count;
}
count = 0;
while (count <= 100)
{
Response.Write(numbers[count] + "<br />");
++count;
}

You need to reset the count to 0 before you attempt the next while statement. Currently, the first loop ends when it reaches a count equal to 101. WHen you proceed to the next while, the count is 101 so the loop automatically ends. Just set count = 0; before the second while loop.

This seems like a very convoluted and unrealistic way of using while loops and arrays. In order to understand it better, it may be worth thinking about it per step.
var i = 0;
while (i < 100)
{
Response.Write(++i + "<br />");
}
The first important distinction is between i++ and ++i. The former utilises the value, and then increments by one; the latter, increments the number and then utilises the value.
In C#, you should really be working with Collections, rather than Arrays. Arrays are zero-indexed, and are renowned for causing serious errors, including exposing potential exploits. Being statically allocated, there is no failsafe when attempting to access indicies outside of the bounds of the Array. Collections, on the other hand, are (for the most part) one-indexed, dynamically allocated, and provide fallbacks when accessing indicies. The most commonly used Collection is a List.
var i = 1;
var list = new List<int>();
while (i <= 100)
{
list.Add(i++);
}
For the second while loop, it's not really suitable to use a while loop here, for any practical example. The excercise is forcing while loops where they are not needed. In this instance, the aim is to iterate through each element in the array (List) and dump its contents to the screen. Because we want to perform an action for each element, a while loop may cause issues. If the array has less than 100 elements, the program will crash, if the array has more than 100 elements, we'll miss some of them. By using a foreach loop, instead of a while, we can eliminate these potential errors.
foreach (var num in list)
{
Response.Write(num + "<br />");
}
Now, I realise that the excercise is about while loops, however, it is teaching you to use them in the wrong way. A much better way - and how you'll most often use them - is to perform an action until a particular condition is met, rather than for simple iteration. By this, I mean, a condition is set to false, then inside the while loop, we manipulate a variable, test the condition, and if it's still false, we go round again. The most common example of this is to work out factorials of numbers.
var num = 5;
var factorial = 1;
while (counter > 1)
{
factorial *= num--;
}
Response.Write(String.Format("{0}! = {1}", input, factorial));
The other main way in which while loops are used is to force an infinite loop, unless a break condition is met. I'll show a very arbitrary use of this here, but a real world example would be the loop() method in Arduino C coding, or a HTTP Listener that constantly repeats the same procedures, until stopped.
var stop = 13;
Response.Write("Pick a number between 1 and 100...<br /><br />");
while (true)
{
var num = new Random().Next(1, 101);
Response.Write(num + " ..... ");
if (num == stop) break;
Response.Write("You got lucky!<br />");
}
Response.Write("Unlucky for you!);
The best way to learn these things is to practice them. Pick a task and find out just how many ways there are to complete it. There is one last important distinction to mention though. a while loop tests the condition at the beginning of the loop. A do while loop, tests the condition at the end.
while(false)
{
// This code will never be run.
}
Compared to:
do
{
// This code will be run once only.
}
while(false)
As a final thought, here's how I'd write the original code (using a LINQ foreach loop):
var numbers = new List<int>();
for (var count = 1; count <= 100; count++)
{
numbers.Add(count);
}
numbers.ForEach(num => Response.Write(num + "<br />")));