Question

How to check whether a string contains duplicate characters in C#

Answer 1

using System;
using System.Linq;

class Program
{
    static void Main() {
        String s = "c# program-ing"; 
       
        bool b = s.Where((ch, i) => i > 0 && ch == s[i - 1] )
                         .Cast<char?>()
                         .FirstOrDefault() != null;
                         
        Console.WriteLine(b);
    }
}




/*
run:

False

*/

 

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Answer 2

using System;

class Program
{
    static bool contains_duplicate_characters(string s) {
        if (string.IsNullOrEmpty(s)) return false;
    
        bool b = false;
        for (int i = 0 ; i < s.Length - 1 && !b; i++) {
            b = s[i] == s[i + 1];
        }
    
        return b;
    }
    static void Main() {
        String s = "c# program-ingg"; 
       
        Console.WriteLine(contains_duplicate_characters(s));
    }
}




/*
run:

True

*/

 

Cleaner teeth, healthier you!
Get The Secret to a Bright and Healthy Smile