c#-how to delete vowels in an array of string?

Question

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

namespace myApp  
{    
    class Program
    {
        static void Main(string[] args)
        {
            string[] vowels = new string[]{"A","a","E","e","I","i","O","o","U","u"};
            for(int j=0;j<vowels.Length;j++)
            {
                string[] names = new string[5];
                names[0] = "john";
                names[1] = "samuel";
                names[2] = "kevin";
                names[3] = "steve";
                names[4] = "martyn";
            for (int i = 0; i < names.Length; i++)
            {
               if(vowels[j]==names[i])
               {

               }
            }


                Console.WriteLine("The output is:"+names[i]);
            }
                Console.ReadLine();
        }
    }
}

can anyone help me how to delete the vowels from the given names and display them in console?

Answer 1

You can use Linq for it

string[] names = new string[5];
names[0] = "john";
names[1] = "samuel";
names[2] = "kevin";
names[3] = "steve";
names[4] = "martyn";

var vowels = new HashSet<char>("AaEeIioUu");


names = names.Select(Name => string.Concat(Name.Where(C => !vowels.Contains(C))))
             .ToArray();

Console.WriteLine(string.Join(Environment.NewLine, names));

Answer 2

You can use Regex.Replace:

Regex r = new Regex("[aAeEiIoOuU]");
//or Regex r = new Regex("[aeiou]", RegexOptions.IgnoreCase);
string[] names = new string[5];
names[0] = "john";
names[1] = "samuel";
names[2] = "kevin";
names[3] = "steve";
names[4] = "martyn";

for (int i = 0; i < names.Length; i++)
{
    names[i] = r.Replace(names[i], "");

    Console.WriteLine("The output is:" + names[i]);
}

To make your original approach work you need to add a call to string.Replace:

names[i] = names[i].Replace(vowels[j], "");

That says "replace any occurances of vowels[j] in names[i] and assign the result to names[i]".

However, you are currently declaring your array of names inside your vowel loop so you're not going to quite get the result you expect if you add the replacement code.

You're also looping around the vowels and then the names; logically it probably makes sense to reverse this - that certainly makes outputting the results easier. Something like this should work for you:

string[] vowels = new string[] { "A", "a", "E", "e", "I", "i", "O", "o", "U", "u" };

string[] names = new string[5];
names[0] = "john";
names[1] = "samuel";
names[2] = "kevin";
names[3] = "steve";
names[4] = "martyn";

for (int i = 0; i < names.Length; i++)
{
    for (int j = 0; j < vowels.Length; j++)
    {
        names[i] = names[i].Replace(vowels[j], "");
    }

    Console.WriteLine("The output is:" + names[i]);
}

Edit

In the comments the OP asked for an example without using Replace. Here is one such method (@Eser has another in their answer). This approach iterates each character of the input string until it finds a vowel. At that point the characters that have been read up until then (excluding the vowel) are added to a StringBuilder:

public static string RemoveVowels(string name)
{
    StringBuilder noVowels = new StringBuilder();

    //keep track of the last index we read
    int lastIndex = 0;

    int i;
    for (i = 0; i < name.Length; i++)
    {
        if (vowels.Contains(name[i]))
        {
            //the current index is a vowel, take the text from the last read index to this index
            noVowels.Append(name, lastIndex, i - lastIndex);
            lastIndex = i + 1;
        }
    }

    if (lastIndex < i)
    {
        //the last character wasn't a vowel so we need to add the rest of the string here.
        noVowels.Append(name, lastIndex, name.Length - lastIndex);
    }

    return noVowels.ToString();
}

The above method can be called for each name in your array:

for (int i = 0; i < names.Length; i++)
{
    Console.WriteLine("The output is:" + RemoveVowels(names[i]));
}

As to which approach to use, I would go with the one you find the most readable unless you have some specific performance requirements at which point I think you'd need to measure each approach and pick the one that fits your requirements best.

Answer 3

First, you need a nested loop if you are to work on an array of name. You have to loop through your names then inside loop through each vowel. Then use String.Replace to complete the process.

name = name.Replace(vowels[j], String.Empty);

Answer 4

I think this is the easiest option:

static void Main(string[] args)
{
    string[] names = new string[] { "john", "samuel", "george", "steve", "martyn" };

    foreach (var name in names)
    {
        string withoutVowels = new string(name.Where(x => !"aeiou".Contains(x)).ToArray());
        Console.WriteLine("The output is: " + withoutVowels);
    }
    Console.ReadKey();
}

If you happen to need it for uppercase too, just use this line instead:

string withoutVowels = new string(name.Where(x => "aeiou".IndexOf(x.ToString(), StringComparison.InvariantCultureIgnoreCase) < 0).ToArray());

Of course, you could also use "aeiouAEIOU" and stick to the first option.

Just for the sake of it, extremely short version, based on Eser's answer:

static void Main(string[] args)
{
    string[] names = new string[] { "johnE", "samuel", "george", "steve", "martyn" };
    Console.WriteLine(string.Join(Environment.NewLine, names.Select(s => new string(s.Where(x => !"aeiou".Contains(x)).ToArray()))));
}

Answer 5

Eser's answer is the most succinct and correct way to do this, but in case you want to more fine-grain control over when and which vowels you're removing, you could also try something like:

string[] names = new string[5];
names[0] = "john";
names[1] = "samuel";
names[2] = "kevin";
names[3] = "steve";
names[4] = "martyn";

List<char> vowels = new List<char>("AaEeIiOoUuYy".ToCharArray());

for(int i = 0; i < names.Length; i++) {
    string name = names[i];
    string trimmedName = name;

    foreach(char vowel in vowels) {
        int vowelIndex;
        while((vowelIndex = trimmedName.IndexOf(vowel)) != -1) {
            trimmedName = trimmedName.Substring(0, vowelIndex) + trimmedName.Substring(vowelIndex + 1);
        }

    }
    name = trimmedName;
}

This is a bit more explicit, less performant, and definitely more ugly though -- so you may want to go with the original solution.

Answer 6

forech(string s in strings)
{
    s.Replace("a", "");
    // etc
}

Answer 7

You could use ToUpper / ToLower to check for the vowels so you don't have to have to list the vowels twice (once for each casing).

First loop through each name, then from each name loop through each vowels. Then, remove the matching vowel with .Replace()

Here is the working example:

fiddle: https://dotnetfiddle.net/STnyWE

using System;    

public class Program
{
  public static void Main()
  {
    string[] vowels = new string[]{"A","E","I","O","U"};


            string[] names = new string[5];
            names[0] = "john";
            names[1] = "samuel";
            names[2] = "kevin";
            names[3] = "steve";
            names[4] = "martyn";

            for (int i = 0; i < names.Length; i++)
            {
                foreach(var v in vowels)
                {

                    if(names[i].ToString().ToUpper().Contains(v.ToString()))
                    {
                        Console.WriteLine(names[i]);
                        names[i] = names[i].ToString().ToUpper().Replace(v.ToString(), "");
                        Console.WriteLine("The output is: "+names[i].ToString().ToLower());
                    }
                }
            }

            Console.ReadLine();
   }
}