Cool!

no you havnt ur blind

Got it, you're right! Thx! 🙏🏻

However, test cases do not test Unicode, only ASCII.

"Never do that!" sounds extreme. The intention of Kumite is to challenge and not repeat past solutions.

This was to similar to the previous 🤷🏻

    public static int SameCase(char a, char b)
    {
        if (!char.IsLetter(a) || !char.IsLetter(b)) return -1;
        return char.ToUpper(a) == char.ToUpper(b) ? 1 : 0;
    }

Because Unicode

Because Unicode

TRUE! I've seen it on a map. 🔭😏

you are wrong because the earht is flat

Boxing won't occur here.

char.IsUpper takes a char and returns a bool.

bool (or System.Boolean) has a Equals(bool) override, so the compiler won't choose the Object.Equals(Object) method.

Using == is still better practice, though, as

1. it's more idiomatic; and
2. it avoids having to perform a method call (Equals), though the I'm nearly positive bool.Equals(bool) would be inlined

The ValueType class that all structs implicitly inherit don't have a generic implementation so only the object base class' .Equals method is implemented, meaning you'll have to go through expensive boxing for a simple comparison. This can even involve reflection

See here https://source.dot.net/#System.Private.CoreLib/src/System/ValueType.cs

Fortunately, seemingly all value types provided by .NET implement their own .Equals method to avoid boxing. So do record structs

Fixed.

Task description for C language contains an error in the given example. The length of the array is 23, not 20.

First letter check, after it case check. Then you don't need IsUpper.

public static int SameCase(char a, char b) =>
!(Char.IsLetter(a) && Char.IsLetter(b)) ? -1 : (Char.IsLower(a) == Char.IsLower(b) ? 1 : 0);

I like your point about matching the letter cases, but the initial problem assumes there will be tests without letters (i.e. Kata.SameCase( 'a', '~') ) for which you should output '-1'.

public class Kata {
  public static int SameCase(char a, char b) =>(char.IsLower(a) == char.IsLower(b))? 1 : 0;
}

If you are calling this function you are working on letters so don't bother checking for that. You also can use == instead of checking for true values since technically two false values would suffice as well (meaning that both letters are uppercase).