如何檢查字符串 c# 中的重復字母

Question

我正在創建一個檢查字符串中重復字母的程序。

例如：

嗚嗚嗚
快樂的

這是我的代碼：

 string repeatedWord = "woooooooow";
 for (int i = 0; i < repeatedWord.Count(); i++)
 {
     if (repeatedWord[i] == repeatedWord[i+1])
     {
          // ....
     }
 }

該代碼有效，但總是會出錯，因為最后一個字符[i + 1]為空/null。

錯誤是索引超出了數組的范圍。

有什么解決辦法嗎？

Answer 1

運行循環直到repeatedWord.Count()-1

Answer 2

另一種選擇是使用匹配重復字符的正則表達式。 然后，對於每個匹配項，您可以使用Length屬性獲取字符數。

string input = "wooooooow happppppppy";
var matches = Regex.Matches(input, @"(.)\1+");
for (int i = 0; i < matches.Count; i++)
{
    Console.WriteLine("\"" + matches[i].Value + "\" is " + matches[i].Length + " characters long.");
    //...
}
Console.Read();

Answer 3

正則表達式：

Regex rxContainsMultipleChars = new Regex( @"(?<char>.)\k<char>" , RegexOptions.ExplicitCapture|RegexOptions.Singleline ) ;
.
.
.
string myString = SomeStringValue() ;
bool containsDuplicates = rxDupes.Match(myString) ;

或 Linq

string s = SomeStringValue() ;
bool containsDuplicates = s.Where( (c,i) => i > 0 && c == s[i-1] )
                           .Cast<char?>()
                           .FirstOrDefault() != null
                           ;

或滾你自己的：

public bool ContainsDuplicateChars( string s )
{
  if ( string.IsNullOrEmpty(s) ) return false ;

  bool containsDupes = false ;
  for ( int i = 1 ; i < s.Length && !containsDupes ; ++i )
  {
    containsDupes = s[i] == s[i-1] ;
  }

  return containsDupes ;
}

甚至

public static class EnumerableHelpers
{
  public static IEnumerable<Tuple<char,int>> RunLengthEncoder( this IEnumerable<char> list )
  {
    char? prev  = null ;
    int   count = 0 ;

    foreach ( char curr in list )
    {
      if      ( prev == null ) { ++count ; prev = curr ; }
      else if ( prev == curr ) { ++count ;               }
      else if ( curr != prev )
      {
        yield return new Tuple<char, int>((char)prev,count) ;
        prev = curr ;
        count = 1 ;
      }
    }
  }
}

有了這最后一個...

bool hasDupes = s.RunLengthEncoder().FirstOrDefault( x => x.Item2 > 1 ) != null ;

要么

foreach (Tuple<char,int> run in myString.RunLengthEncoder() )
{
  if ( run.Item2 > 1 )
  {
     // do something with the run of repeated chars.
  }
}

Answer 4

只需“記住”我要說的最后一個字母。

string repeatedWord = "woooooooow";
if (string.IsNullOrEmpty( repeatedWord))
    // empty. return, throw whatever.

char previousLetter = repeatedWord[0]; 
for (int i = 1; i < repeatedWord.Count(); i++)
{
    if (repeatedWord[i] == previousLetter)
    {
        // ....              
    }
    else
    previousLetter = repeatedWord[i];
}

Answer 5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Delegate
{
    class Program
    {
       public int repeatcount(string str,char ch)
        {

            var count = 0;
            for (int i = 0; i<str.Length; i++)
            {
                if (ch == str[i])
                {
                    count++;
                }

            }

            return count;
        }
        static void Main(string[] args)
        {
            Console.WriteLine("Enter a string");
            string str = Console.ReadLine();
            Console.WriteLine("Enter to know the reperted char");
            char ch = Convert.ToChar(Console.ReadLine());
            Program obj = new Program();
            int p=obj.repeatcount(str, ch);
            Console.WriteLine(p);


            Console.ReadLine();

        }
    }



}

Answer 6

您可以將循環條件更改為-1 （正如其他人已經指出的那樣），或者您可以通過酷孩子的方式來實現。

var text = "wooooooooooow happpppppppy";
var repeats = text.Zip(text.Skip(1), (a, b) => a == b).Count(x => x);

Answer 7

 public int RepeatedLetters(string word)
        {
            var count = 0;
            for (var i = 0; i < word.Count()-1; i++)
            {
                if (word[i] == word[i+1])
                {
                    count++;
                }
            }
            return count;
        }

Answer 8

using System;

namespace temp1
{
    class Program
    {
        static string str = "proffession";
        static int n = str.Length;
        static string dupstr = "";
        static int cnt = 0;
        static void Main()
        {
            RepeatedCharsString(); 
        }

        public static void RepeatedCharsString()
        {
            for (int i = 0; i < n ; i++)
            {
                for(int j = i + 1; j <= n-1; j++)
                {
                    if (str[i] == str[j])
                    {
                        dupstr = dupstr + str[i];
                        cnt = cnt + 1;
                    }
                }                
            }
            Console.WriteLine("Repeated chars are: " + dupstr);
            Console.WriteLine("No of repeated chars are: " + cnt);
        }
    }
}

Answer 9

你也可以這樣做：

string myString = "longstringwithccc";
var list = new List<char>();
var duplicates = new List<char>();
foreach(char c in myString)
{
   if (!list.Contains(c))
   {
      list.Add(c);
   }
   else
   {
      if (!duplicates.Contains(c))
      {
         duplicates.Add(c);
      }
   }
}

duplicates將包含原始字符串中的重復字符。

list將包含刪除重復項的原始字符串。

Answer 10

您可以按如下方式找到第一個不重復的數字。

    static string intputString = "oossmmaanntuurrkt";
    static void Main(string[] args)
    {

        Console.WriteLine(OutPutValue(intputString));
        Console.ReadLine();
    }

    public static char OutPutValue(string strValue)
    {
        Dictionary<char, int> repeatValue = new Dictionary<char, int>();

        char[] arrValue = intputString.ToCharArray();

        foreach (var item in arrValue)
        {
            int repearCount = 0;
            if (repeatValue.ContainsKey(item))
            {
                repeatValue[item] = repeatValue.FirstOrDefault(t => t.Key == item).Value + 1;
            }
            else
            {
                repearCount++;
                repeatValue.Add(item, repearCount);
            }

        }

        return repeatValue.FirstOrDefault(t => t.Value == 1).Key;
    }

您可以獲得如下的重復次數和次數信息。

repeatValue.Where(t=> t.Value > 1)

Answer 11

您運行循環一次迭代的時間太長。

或者，您可以使用 LINQ 查找單詞中的唯一（不同）字符，然后檢查它們在單詞中的出現次數。 如果它出現不止一次，請對其進行處理。

void RepeatedLetters()
{
    string word = "wooooooow";
    var distinctChars = word.Distinct();
    foreach (char c in distinctChars)
        if (word.Count(p => p == c) > 1)
        { 
            // do work on c
        }
}

Answer 12

使用 C# 在給定字符串中查找重復或重復的字母

string str = "Welcome Programming";
char[] Array = str.ToCharArray();
var duplicates = Array.GroupBy(p => p).Where(g => g.Count() > 1).Select(g => g.Key).ToList();
string duplicateval= string.Join(",", duplicates.ToArray());

輸出：

e,o,m,r,g