Made WCharacter.h more clear

[pratikpc]

It's obvious that a == 0 ? false : true is same as a != 0

Also a != 0 looks more clear as a Return Type to a bool function.
It's more easier to understand what it does in this form.
WCharacter.h was full of functions which utilised a == 0 ? false : true instead of the more easy to read a != 0 which strikes a fine balance between simplicity and readability.

If we are to look at Standard Library Definitions of the various functions used like isdigit, isalpha etc. we find they return 0 when they do not find anything thus making isdigit(ch) != 0 even more clearer

Added extern C
Given the fact that we are using C Functions and code that is compatible with the C Standard, I added extern C. Extern C is also used in similar C Standard Compatible Arduino header files

[CLAassistant]

All committers have signed the CLA.

[leg0]

This is useless. It only changes how the function names are mangled. Since the functions are not compiled into an object file nor a static library, it doesn't matter if they're extern "C" or not. They're inline, in C++ and in C.

[matthijskooijman]

I don't think this is true for any inline function, since they are not necessarily inlined. In this case, they are always_inline so it should indeed not matter, but it might be good to still have the extern "C" for good measure (and in case other non-always_inline functions are added later). I would omit the comment here, though, since the meaning/intention of extern "C" is rather obvious (and can be looked up if not) and I believe it's used without comment elsewhere too.

[matthijskooijman]

Looks like a reasonable change to me. As @leg0 suggests, extern "C" is not strictly required, but it doesn't hurt. I can imagine removing the comment about it, though. See also inline comment.

[matthijskooijman]

I don't think this is true for any inline function, since they are not necessarily inlined. In this case, they are always_inline so it should indeed not matter, but it might be good to still have the extern "C" for good measure (and in case other non-always_inline functions are added later). I would omit the comment here, though, since the meaning/intention of extern "C" is rather obvious (and can be looked up if not) and I believe it's used without comment elsewhere too.

[aentinger]

Hi @leg0 👋 Can you please sign the CLA?

[leg0]

@aentinger I have already signed it.

[per1234]

We need @pratikpc to sign the CLA:
https://cla-assistant.io/arduino/ArduinoCore-API?pullRequest=26

[aentinger]

@aentinger I have already signed it.

Mea culpa 😊

[aentinger]

@pratikpc can you please sign it while being logged in via the right email ... likely the email stored in the commit is different from the one you are signed in GitHub.