How do I alternate the case in a string?

Question

I need to alternate the case in a sentence and I don't know how to. For example:

thequickbrownfoxjumpsoverthelazydog

to

GoDyZaLeHtReVoSpMuJxOfNwOrBkCiUqEhT

this is my code so far

Console.WriteLine("Please enter a sentence:");
        string text = Console.ReadLine();
        text = text.Replace(" ", "");
        char[] reversed = text.ToCharArray();//String to char
        Array.Reverse(reversed);//Reverses char
        new string(reversed);//Char to string

        Console.WriteLine(reversed);
        Console.ReadLine();

Please note that there are no spaces for a reason as that's also part of the homework task.

What have you tried? This is somewhat trivial and you should at least have some code to show before we help you. — Simon Belanger, Jul 06 '14 at 12:29
why are you reversing chars ? or did you just copy paste that code from another question? — Selman Genç, Jul 06 '14 at 12:33

score 2 · Answer 1 · answered Jul 06 '14 at 12:36

2

A string is immutable, so, you need to convert it to a char[].

char[] characters = text.ToCharArray();
for (int i = 0; i < characters.Length; i+=2) {
    characters[i] = char.ToUpper(characters[i]);
}
text = new string(characters);

answered Jul 06 '14 at 12:36

Dennis_E

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Soner Gönül · Accepted Answer · 2014-07-06T12:43:38.890

1

There is no point to reverse your string. Just upper case your even number indexed characters in your string.

Remember, my culture is tr-TR and this String.ToUpper method works depends on your current thread culture. In this example, your output can be different than mine.

Here an example in LINQPad;

string s = "thequickbrownfoxjumpsoverthelazydog";
StringBuilder sb = new StringBuilder();
for (int i = 0; i < s.Length; i++)
{
    if (i % 2 == 0)
    {
        sb.Append(s[i].ToString().ToUpper());
    }
    else
    {
        sb.Append(s[i].ToString());
    }
}
sb.ToString().Dump();

Output will be;

ThEqUiCkBrOwNfOxJuMpSoVeRtHeLaZyDoG

edited Jul 06 '14 at 12:43

answered Jul 06 '14 at 12:35

Soner Gönül

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The alternating worked, thanks. and also, reversing was part of the homework task – musiclover Jul 06 '14 at 12:43
@musiclover Take a look at [Best way to reverse a string](http://stackoverflow.com/questions/228038/best-way-to-reverse-a-string) – Soner Gönül Jul 06 '14 at 12:45

score 0 · Answer 3 · answered Jul 06 '14 at 13:35

Another possible solution with LINQ can be done in one line like this:

string s = "thequickbrownfoxjumpsoverthelazydog";
string result = new String(s
                            // take each character
                            .ToCharArray()
                            // convert every character at even index to upper
                            .Select ((character, index) => (index % 2) == 0 ? Char.ToUpper(character) : character)
                            // back to array in order to create a string
                            .ToArray());
Console.WriteLine(result);

The output is:

ThEqUiCkBrOwNfOxJuMpSoVeRtHeLaZyDoG

This solution uses the indexed LINQ Select clause in order to access the current index and the value that is currently projected.

score 0 · Answer 4 · answered Mar 08 '18 at 22:52

A one liner:

new string(myString.Select((c, i) => i % 2 == 0 ? char.ToUpper(c) : c).ToArray())

An extension method:

 public static string AltCase(this string s)
 {
     return new string(s.Select((c, i) => i % 2 == 0 ? char.ToUpper(c) : c).ToArray());
 }

How do I alternate the case in a string?

4 Answers4