Check if lowercase and uppercase alternate

Question

string s = "This is an ExAmPlE of sTrInG";

Such words in this string: 2.

I understand how to convert a phrase to uppercase and lowercase words but i dont know how to find such words in string and count it

Should they alternate exactly or just select words that contain both upper and lower case letters? — mousetail, Mar 22 '21 at 10:34
Just go over the words in a loop and check for each character? — Max Play, Mar 22 '21 at 10:35
why is `ExAmPLE` alternating while `This` is not? Would `Example` be alternating? — MakePeaceGreatAgain, Mar 22 '21 at 10:35
yes. they should alternate. Max, is there a way to do this without using a loop? — Solar1888, Mar 22 '21 at 10:36
@HimBromBeere it's `ExAmPlE`, not `ExAmPLE` (alternating meaning 1up/1low/1up/1low...) — Rafalon, Mar 22 '21 at 10:38
how do you iterate through a string without a loop? unless the string always has a fixed length — phuclv, Mar 22 '21 at 10:38
HimBromBeere, in my question " ExAmPlE" and "sTrInG". in these words capital letters alternate with lowercase — Solar1888, Mar 22 '21 at 10:39
Do you have any requirement regarding what you consider to be "Upper" and "Lower"? Depending on your requirements, you could use `char.IsUpper(c1) != char.IsUpper(c2)` to check that two chars don't have the same case. Or you could use `char.IsLower(c1) != char.IsLower(c2)`. Or you have to use `char.IsLower(c1) && char.IsUpper(c2) || char.IsUpper(c1) && char.IsLower(c2)`. Edge cases include having digits or non-alphanumeric characters — Rafalon, Mar 22 '21 at 10:57

score 0 · Answer 1 · edited Mar 25 '21 at 09:33

0

This should do the trick:

First you need to split the string in words and than you can check each word if is alternating

    public void Counter(string phrase)
    {
        var qty = 0;
        var words = phrase.Split(' ');
        for (var i = 0; i < words.Length; ++i)
        {
            if (IsUpperLowerAltenated(words[i].Trim()))
                ++qty;
        }


    }


    public bool IsUpperLowerAltenated(string word)
    {
        for (var i = 1; i < word.Length; ++i)
        {
            if(char.IsLower(word[i-1]) == char.IsLower(word[i]))
               return false;
        }
        return true;
    }

edited Mar 25 '21 at 09:33

Rafalon

4,450
2
16
30

answered Mar 22 '21 at 10:50

Stefano Cavion

641
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16

You could just replace the whole content of your loop (inside `IsUpperLowerAlternated`) with `if(char.IsLower(chars[i-1]) == char.IsLower(chars[i])) return false;` – Rafalon Mar 22 '21 at 11:04
@Rafalon you are right feel free to improve it – Stefano Cavion Mar 22 '21 at 15:43

JL0PD · Answer 2 · 2021-03-22T10:55:33.940

String is mixed case if it's not either lower or upper

bool IsUpper(string str) => str.Upper() == str;
bool IsLower(string str) => str.Lower() == str;

bool IsMixedCase(string str) => !IsUpper(str) && !IsLower(str);

string s = "This is an ExAmPlE of sTrInG";
foreach (var str in s.Split().Where(IsMixedCase))
{
    Console.WriteLine(str);
}

Update

Solution without explicit loop. String is alternating if each pair of characters in different cases

public static IEnumerable<(T, T)> Pairwise<T>(this IEnumerable<T> input) 
    => input.Zip(input.Skip(1), (a, b) => (a, b));

public static bool OfDifferentCase(char c1, char c2) 
    => char.IsUpper(c1) && char.IsLower(c2) || char.IsLower(c1) && char.IsUpper(c2);

public static bool IsAlternating(string str) 
    => str.Pairwise().All(p => OfDifferentCase(p.Item1, p.Item2));

string s = "This is an ExAmPlE of sTrInG";
foreach (var str in s.Split().Where(IsAlternating))
{
    Console.WriteLine(str);
}

OP doesn't seem to be looking for "mixed case" so it's not *that simple*, but I think that using a function that determines what you want is a good strategy (`bool IsAlternatingCase(string str)`) then all OP has to do is implement this — Rafalon, Mar 22 '21 at 10:41

score -1 · Answer 3 · answered Mar 22 '21 at 10:57

You can find count of upper and lower chars like this.

public int IsUpperCount(string myString)
{   int upperC=0;
    var charArray = myString.ToCharArray();
    foreach (var item in charArray)
    {
     if(item.toString()==item.toString().ToUpper())
     { upperC++;}
 return upperC;
}

public int IsLowerCount(string myString)
{   int lowerC=0;
    var charArray = myString.ToCharArray();
    foreach (var item in charArray)
    {
     if(item.toString()==item.toString().ToUpper())
     { lowerC++;}
return lowerC;
}

`ExAmPlE` is alternating and does not have same count of upper and lower chars (4 vs 3). Reversely, `EXAmpl` have the same count and isn't alternating. I don't see how this answer can help determining if a word is alternating or not — Rafalon, Mar 22 '21 at 11:00

score -1 · Answer 4 · answered Mar 22 '21 at 16:50

string s = "This is an ExAmPlE of sTrInG";

var words = Regex.Matches(s, @"\b((\p{Ll}\p{Lu})+\p{Ll}?|(\p{Lu}\p{Ll})+\p{Lu}?)\b");

foreach (var w in words)
{
    Console.WriteLine(w);
}

Reference:
Regex pattern search for alternating character case
RegEx for matching alternating case letters
Make regular expression not match empty string?
regex - match pattern of alternating characters
Supported Unicode general categories

Check if lowercase and uppercase alternate

4 Answers4

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