C# find the count of duplicate characters in an array and list them

Question

I am trying to find the number of duplicate characters in an array and list them. For example, the user enters "this is my house", the output should look like this:

Number of duplicate characters is: 3 and the duplicates are: h i s

I have to use ToCharArray()

I've been trying but I can't get it to work properly, can you please help?

Thanks

Here is my code:

using System;
class Program
{
    static void Main()
    {
        Console.Write("type a sentence: ");
        String str = Console.ReadLine();
        char[] arr = str.ToCharArray();

        for (int j = 0; j < arr.Length; j++)
        {
            for (int k = j + 1; k < arr.Length; k++)
            {
                if (arr[j] == arr[k] && j != k)
                {
                    Console.WriteLine("number of duplicates: " + k + "\n" + "duplicates are: " + arr[j]);
                    Console.ReadLine();
                }
            }
        }
    }
}

github.com/morelinq/MoreLINQ/issues/125 may be of interest.

mjwills
– mjwills

2018-11-11 06:30:20 +00:00
Commented Nov 11, 2018 at 6:30 — mjwills
– mjwills, Commented Nov 11, 2018 at 6:30

D-Shih · Accepted Answer · 2018-11-11 05:03:14Z

5

You can try to use linq instead of for loop.

GroupBy make a group and use where get count greater than 1.

var r= str.Replace(" ", "").GroupBy(_ => _).Where(x => x.Count() > 1).Select(x => x.Key);

then use string.Join method and linq count instead of a loop to get your expect result.

Console.Write("type a sentence: ");
String str = Console.ReadLine();


var result = str.Replace(" ", "")
     .GroupBy(_ => _)
     .Where(x => x.Count() > 1)
     .Select(x => x.Key);


Console.WriteLine("number of duplicates: " + result.Count() + "\r" + "duplicates are: " + string.Join(" ",result));

c# online

Result

type a sentence: number of duplicates: 3  duplicates are: h i s

edited Nov 11, 2018 at 5:03

answered Nov 11, 2018 at 4:56

D-Shih

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2 Comments

Nas Over a year ago

thanks but I can't use Linq, this is an assignment and we are limited, I have to use a simple code like the above, my issue is that I can't get it to count or list properly.

D-Shih Over a year ago

@Nas Ok I edit my answer it can show like your expect result

Eray Balkanli · Accepted Answer · 2018-11-11 05:06:25Z

0

Here is another solution without linq:

static void Main(string[] args)
{
    string longText = @"your sentence comes here";
    foreach (var character in CharacterCount.Count(longText))
    {
        if(character.Value>1)
           Console.WriteLine("{0} - {1}", character.Key, character.Value);
    }    
}

class CharacterCount
{
    public static SortedDictionary<char, ulong> Count(string stringToCount)
    {
        SortedDictionary<char, ulong> characterCount = new SortedDictionary<char, ulong>();

        foreach (var character in stringToCount)
        {
            if (!characterCount.ContainsKey(character))
                characterCount.Add(character, 1);
            else
                characterCount[character]++;
        }
        return characterCount;
    }   
}

answered Nov 11, 2018 at 5:06

Eray Balkanli

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1 Comment

mjwills Over a year ago

Consider using TryGetValue rather than ContainsKey.

Chameera · Accepted Answer · 2018-11-16 11:51:28Z

0

This may help.

    Console.Write("type a sentence: ");
    String str = Console.ReadLine();
    char[] arr = str.ToCharArray();

    int[] count = new int[10000];

    for (int j = 0; j < arr.Length; j++)
    {
        if( arr[j] >= 'a' && arr[j] <= 'z' || arr[j] >= 'A'&& arr[j] <= 'Z' )
        {
            count[arr[j]]++;
        }
    }

    int ans=0;
    for (int j = 0; j < count.Length; j++)
    {
        if(count[j]>1)
        {
            ans++;              
        }
    }

    Console.Write("Number of duplicates: " + ans +" duplicates are: ");

    for (int j = 0; j < count.Length; j++)
    {
        if(count[j]>1)
        {
            Console.Write((char)j +" " );
        }
    }
    Console.WriteLine();
}

edited Nov 16, 2018 at 11:51

answered Nov 11, 2018 at 5:15

Chameera

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1 Comment

Nas Over a year ago

Thanks Chameera, it works, just couple of notes, it is taking the Space as a character (for example "this is my house" is showing as 4 duplicates instead of 3), how can we avoid that. and also is it possible to list the duplicates on the same line instead of each on a separate line?

Shrawan · Accepted Answer · 2021-02-02 16:58:01Z

This Find to find Duplicates characters And Its Occurrence and I am using Key value pair in C# 
    /// <summary>
    /// Find The Duplicates And Its Occurrence
    /// </summary>
    /// <param name="inputString"> input String for example 
    /// "Aassekoopannessyttoodde","Mississippi","raccoonnookkeeper"</param>
    private static void FindTheDuplicatesAndItsOccurrence(string inputString)
    {
        // we used Dictionary to make this collection generic  
        Dictionary<Char, int> CharCount = new Dictionary<char, int>();

        foreach (Char eachLetter in inputString)
        {
            if (eachLetter != ' ')
            {
                if (!CharCount.ContainsKey(eachLetter))
                {
                    CharCount.Add(eachLetter, 1);
                }
                else
                {
                    CharCount[eachLetter]++;
                }
            }
        }
        
        foreach (var item in CharCount)
        {
            if (item.Value > 1)
            {
                Console.WriteLine(item.Key + "," + item.Value);
            }
            
        }
    }

CDspace · Accepted Answer · 2024-01-24 23:03:26Z

0

Finding duplicate characters and there count using linq

using System;
using System.Linq;
using System.Collections.Generic;
                    
public class Program
{
    public static void Main()
    {
        string myName = "Hussamuddin";
        List<char> elementCount =  new List<char>(myName.ToCharArray());
        var mycount = elementCount.Where(x => myName.Contains(x)).GroupBy(x=>x).Where(x => x.Count()>1).Select(x => x.Key + ":" + x.Count().ToString()).ToList();
        mycount.ForEach(x => Console.WriteLine(x));
    }
}

Output:

u:2
s:2
d:2

edited Jan 24, 2024 at 23:03

CDspace

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answered Jan 19, 2024 at 15:50

mohammed hussamuddin hussamudd

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