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Performing linear search on randomized array

I am trying to perform a linear search on some randomized array, but just cant see where the code gets stuck. Its a simple BigONotation algorithm test that I am currently learning and messed up somewhere. I am using a text editor for my coding. Can I get some help with this code?
using System;
using System.Collections.Generic;
using System.Data;
namespace TheBigONotations
{
public class BigONotations
{
///<properties>Class Properties</properties>
private int[] theArray;
private int arraySize;
private int itemsInArray = 0;
DateTime startTime;
DateTime endTime;
public BigONotations(int size)
{
arraySize = size;
theArray = new int[size];
}
///<order>O(1)</order>
public void addItemToArray(int newItem)
{
theArray[itemsInArray++] = newItem;
}
///<order>O(n)</order>
public void linearSearch(int value)
{
bool valueInArray = false;
string indexsWithValue = "";
startTime = DateTime.Now;
for (int i = 0; i < arraySize; i++)
{
if (theArray[i] == value)
{
valueInArray = true;
indexsWithValue += i + " ";
}
}
Console.WriteLine("Value found: " + valueInArray);
endTime = DateTime.Now;
Console.WriteLine("Linear Search took "+(endTime - startTime) );
}
///<order>O(n^2)</order>
public void BinarySearch()
{
}
///<order>O(n)</order>
///<order>O(n)</order>
///<order>O(n)</order>
public void generateRandomArray()
{
Random rnd = new Random();
for (int i = 0; i < arraySize; i++)
{
theArray[i] = (int)(rnd.Next() * 1000) + 10;
}
itemInArray = arraySize - 1;
}
public static void Main()
{
BigONotations algoTest1 = new BigONotations(100000);
algoTest1.generateRandomArray();
BigONotations algoTest2 = new BigONotations(200000);
algoTest2.generateRandomArray();
BigONotations algoTest3 = new BigONotations(300000);
algoTest3.generateRandomArray();
BigONotations algoTest4 = new BigONotations(400000);
algoTest4.generateRandomArray();
BigONotations algoTest5 = new BigONotations(500000);
algoTest5.generateRandomArray();
algoTest2.linearSearch(20);
algoTest3.linearSearch(20);
algoTest4.linearSearch(20);
}
}
}
I put all information in the code but had some error and cant see exactly where it is.

I think the error is because itemInArray inside generateRandomArray() function is not declared. Perhaps you meant itemsInArray?
String addition (with + and += operator) for too many results might be taking long time during linearSearch(). Consider using StringBuilder which is significantly faster and more memory efficient.
StringBuilder sb = new StringBuilder();
// ...
// Let's say "i" is an integer.
sb.Append(i.ToString());
sb.Append(" ");
// ...
Console.WriteLine("Indexes: " + sb.ToString());

C# Sliding Window Algorithm

So i have to sent a message from a Sender to a Destination(Shown in main class) by specifing how many letters i wanna sent (the size variable).When the laters left are less than letters i wanna sent,it automaticaly sent how many i have left,and after the algorithm stops;
The problem is when the message i supossely sent is 9 characters long,and when i wanna sent 6 characters and another 3 it throws me an error (System.IndexOutOfRangeException: 'Index was outside the bounds of the array.'
)
using System;
using System.Text;
using System.Threading;
namespace homework
{
internal class slidingWindow
{
private string name;
private StringBuilder message = new StringBuilder();
private bool isSource = false;
private int fin = 0;
public slidingWindow(string name, bool isSource)
{
this.name = name;
this.isSource = isSource;
}
public void messageSet(string _message)
{
if (isSource == true) message.Append(_message);
else Console.WriteLine("Is not source");
}
public void sendMessage(slidingWindow destination)
{
int counter= 0;
Console.WriteLine("Specify the size of data sent: ");
int size = Convert.ToInt32(Console.ReadLine()); //the size of how manny letters i should send
int countCharacterSent=size;
for (int x = 0; x < message.Length+(message.Length%size); x = x + size)
{
counter++;
for (int y = 0; y < size; y++)
{
if (x + size > message.Length + (message.Length % size)) { size=size-(message.Length%size); countCharacterSent = message.Length; }
else {destination.message.Append(message[x + y]); }
}
Console.WriteLine("Sennder---- " + destination.message + " ----->Destination" + " (" + counter+ ")"+ " Characters sent: "+size+ " Characters received: "+countCharacterSent+ '\n');
Thread.Sleep(TimeSpan.FromSeconds(1));
countCharacterSent = countCharacterSent + size;
}
fin = 1;
if (message.Length % size != 0) destination.fin = 1;
destination.print();
}
public void print()
{
Console.WriteLine("Destination has receveid the message: " + message+" FIN: "+fin);
}
}
and the main class
using System;
namespace homework
{
class main
{
static void Main(string[] args)
{
while (true)
{
int option = 0;
slidingWindow a = new slidingWindow("Sender", true);
a.messageSet("exampless");
slidingWindow b = new slidingWindow("Destination", false);
a.sendMessage(b);
Console.WriteLine("If you want to exit write 1:"+'\n');
option = Convert.ToInt32(Console.ReadLine());
if (option == 1) break;
}
}
}
example:
input:
message='example'
size=3;
output:
exa
mpl
e

Honestly I can see you try hard (too hard) to handle the limit case of the last block that can just not meet the expect size.
Since you do this in dotnet C#, and depending on the version you will see you have many different options....
Especially to create a batch of x out of a simple sequence....
here is a homemade version of things you will find for free in libraries like moreLinq and probably in latest Linq lib..
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using System.Linq;
public static class LinqExtensions
{
public static IEnumerable<IEnumerable<T>> Batch<T>(this IEnumerable<T> source, int size)
{
return source
.Select( (c, i) => (c, index : i))
.Aggregate(
new List<List<T>>(),
(res, c) =>
{
if (c.index % size == 0)
res.Add(new List<T> { c.c });
else
res.Last().Add(c.c);
return res;
});
}
}
public class Program
{
public static void Main(string[] args)
{
var test = "xxxxxxxxxxx".AsEnumerable();
var blocks = test
.Batch(3)
.Select(b=> new string(b.ToArray()));
blocks.ToList().ForEach(System.Console.WriteLine);
}
}

Why my C# Code isn't Printing the Required Output

I attempting to create a program that uses multiple methods that would print out base numbers, exponents, and their resulting solutions. I am trying to get it to run and it's nearly completed, but I am encountering a couple issues. The code itself seems to run, but doesn't appear to print out on Visual Studio. I did run it on an online compiler and got this as an output:
It seems I am missing something in my code, but I am unclear as to what I may be missing. This is the code I have created for the project:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Project
{
class Program
{
static void Main(string[] args)
{
//Our initialized variables.
int intMinBase = 1;
int intMaxBase = 100;
int intMinExpo = 1;
int intMaxExpo = 10;
//Our arrays for the project, all at a length of 5.
long[] baseNumbers = new long[5];
long[] exponents = new long[5];
long[] results = new long[5];
//Randomize the baseNumbers and exponents!
Random randInt = new Random();
for (long i = 0; i < 5; i++)
{
baseNumbers[i] = randInt.Next(intMinBase, intMaxBase);
exponents[i] = randInt.Next(intMinExpo, intMaxExpo);
}
PrintArrays(baseNumbers, exponents, results);
}
//This is potentially experimental code for the Power Method.
public static int Power(int baseNum, int exponent)
{
int answer;
if (exponent == 1)
{
answer = 1;
}
else
{
answer = baseNum * Power(baseNum, exponent - 1);
}
return answer;
}
//The new method to be printed. Is this the correct manner to display this?
public static void PrintArrays(long[] baseNum, long[] exponent, long[] result)
{
Console.WriteLine($"Base\tExponent\tResult");
for (int print = 0; print < result.GetUpperBound(0); print++)
{
Console.WriteLine(baseNum[print]+"\t"+exponent[print]+"\t"+result[print]);
}
}
}
}
My question is mainly am I missing something and why isn't it appearing to print in Visual Studio yet it's appearing on an online compiler? I suspect the answer to the first part of the question has to do with the methods I used, but I am unsure.

First error: Nowhere is the method Power called and nowhere is the array results filled.
Solution example:
for (long i = 0; i < 5; i++)
{
baseNumbers[i] = randInt.Next(intMinBase, intMaxBase);
exponents[i] = randInt.Next(intMinExpo, intMaxExpo);
results[i] = Power(baseNumbers[i], exponents[i]);
}

c# comparing list of IDs

I have a List<Keyword> where Keyword class is:
public string keyword;
public List<int> ids;
public int hidden;
public int live;
public bool worked;
Keyword has its own keyword, a set of 20 ids, live by default is set to 1 and hidden to 0.
I just need to iterate over the whole main List to invalidate those keywords whose number of same ids is greater than 6, so comparing every pair, if the second one has more than 6 ids repeated respect to the first one, hidden is set to 1 and live to 0.
The algorithm is very basic but it takes too long when the main list has many elements.
I'm trying to guess if there could be any method I could use to increase the speed.
The basic algorithm I use is:
foreach (Keyword main_keyword in lista_de_keywords_live)
{
if (main_keyword.worked) {
continue;
}
foreach (Keyword keyword_to_compare in lista_de_keywords_live)
{
if (keyword_to_compare.worked || keyword_to_compare.id == main_keyword.id) continue;
n_ids_same = 0;
foreach (int id in main_keyword.ids)
{
if (keyword_to_compare._lista_models.IndexOf(id) >= 0)
{
if (++n_ids_same >= 6) break;
}
}
if (n_ids_same >= 6)
{
keyword_to_compare.hidden = 1;
keyword_to_compare.live = 0;
keyword_to_compare.worked = true;
}
}
}

The code below is an example of how you would use a HashSet for your problem. However, I would not recommend using it in this scenario. On the other hand, the idea of sorting the ids to make the comparison faster still.
Run it in a Console Project to try it out.
Notice that once I'm done adding new ids to a keyword, I sort them. This makes the comparison faster later on.
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
namespace KeywordExample
{
public class Keyword
{
public List<int> ids;
public int hidden;
public int live;
public bool worked;
public Keyword()
{
ids = new List<int>();
hidden = 0;
live = 1;
worked = false;
}
public override string ToString()
{
StringBuilder s = new StringBuilder();
if (ids.Count > 0)
{
s.Append(ids[0]);
for (int i = 1; i < ids.Count; i++)
{
s.Append(',' + ids[i].ToString());
}
}
return s.ToString();
}
}
public class KeywordComparer : EqualityComparer<Keyword>
{
public override bool Equals(Keyword k1, Keyword k2)
{
int equals = 0;
int i = 0;
int j = 0;
//based on sorted ids
while (i < k1.ids.Count && j < k2.ids.Count)
{
if (k1.ids[i] < k2.ids[j])
{
i++;
}
else if (k1.ids[i] > k2.ids[j])
{
j++;
}
else
{
equals++;
i++;
j++;
}
}
return equals >= 6;
}
public override int GetHashCode(Keyword keyword)
{
return 0;//notice that using the same hash for all keywords gives you an O(n^2) time complexity though.
}
}
class Program
{
static void Main(string[] args)
{
List<Keyword> listOfKeywordsLive = new List<Keyword>();
//add some values
Random random = new Random();
int n = 10;
int sizeOfMaxId = 20;
for (int i = 0; i < n; i++)
{
var newKeyword = new Keyword();
for (int j = 0; j < 20; j++)
{
newKeyword.ids.Add(random.Next(sizeOfMaxId) + 1);
}
newKeyword.ids.Sort(); //sorting the ids
listOfKeywordsLive.Add(newKeyword);
}
//solution here
HashSet<Keyword> set = new HashSet<Keyword>(new KeywordComparer());
set.Add(listOfKeywordsLive[0]);
for (int i = 1; i < listOfKeywordsLive.Count; i++)
{
Keyword keywordToCompare = listOfKeywordsLive[i];
if (!set.Add(keywordToCompare))
{
keywordToCompare.hidden = 1;
keywordToCompare.live = 0;
keywordToCompare.worked = true;
}
}
//print all keywords to check
Console.WriteLine(set.Count + "/" + n + " inserted");
foreach (var keyword in set)
{
Console.WriteLine(keyword);
}
}
}
}

The obvious source of inefficiency is the way you calculate intersection of two lists (of ids). The algorithm is O(n^2). This is by the way problem that relational databases solve for every join and your approach would be called loop join. The main efficient strategies are hash join and merge join. For your scenario the latter approach may be better I guess, but you can also try HashSets if you like.
The second source of inefficiency is repeating everything twice. As (a join b) is equal to (b join a), you do not need two cycles over the whole List<Keyword>. Actually, you only need to loop over the non duplicate ones.
Using some code from here, you can write the algorithm like:
Parallel.ForEach(list, k => k.ids.Sort());
List<Keyword> result = new List<Keyword>();
foreach (var k in list)
{
if (result.Any(r => r.ids.IntersectSorted(k.ids, Comparer<int>.Default)
.Skip(5)
.Any()))
{
k.hidden = 1;
k.live = 0;
k.worked = true;
}
else
{
result.Add(k);
}
}
If you replace the linq with just the index manipulation approach (see the link above), it would be a tiny bit faster I guess.

Resolving "An object reference is required for the non-static field" error [duplicate]

This question already has answers here:
CS0120: An object reference is required for the nonstatic field, method, or property 'foo'
(9 answers)
Closed 6 years ago.
I'm facing the following error in C# Visual Studio that I just can't resolve:
"An object reference is required for the non-static field"
I don't know what it means nor how to fix it. Sure, I checked online but didn't find anything that spoke to my simple code below. All I want to do is call the following from Main() successfully:
int result = MaxPair(nums);
Many thanks in advance.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace MaxPairSpace
{
class Program
{
static int Main(string[] args)
{
int n = Int32.Parse( Console.ReadLine() );
string input = Console.ReadLine();
string[] split = input.Split(' ');
int length = split.Length;
int[] nums = new int[length];
for (int x = 0; x < length; x++)
{
nums[x] = Int32.Parse(split[x]);
}
int result = MaxPair(nums);
Console.WriteLine("{0}\n", result);
return 0;
}
public int MaxPair(int[] numbers)
{
int result = 0;
int n = numbers.Length;
for (int i = 0; i < n; ++i)
{
for (int j = i; j < n; ++j)
{
if (numbers[i] * numbers[j] > result)
{
result = numbers[i] * numbers[j];
}
}
}
return result;
}
}
}

You cannot access a non-static method/Variable/Property directly inside a static method. To access such items you need to create an instance of the corresponding class and through that instance you can access them where as you can access other static methods/Variable/Property inside a static method. If such items belongs to a different class then You can access them through their class name. that is, ClassName.Method(). So better option here is to Change the method signature as like the following:
public static int MaxPair(int[] numbers)
{
// Code here
}