Ask HN: How do I learn C properly?

Re:Ask HN: How do I learn C properly? by jstimpfle on Sunday March 08, 2020 @07:21PM (#22521393)

It's not strictly a superset, to the point that there are good reasons to stay with a C compiler other than to simply stay sane. I make a lot of use of designated initializers for laying out static const arrays. And I actually don't like the way that structs in C++ can be referred to both with and without the struct tag. I also don't like how void-pointers are not compatible with other pointers without an explicit cast. Or that plain integers cannot be assigned to enum types. Some of this is just my personal preference (or Stockholm Syndrome), but the fact is that most C code will fail to compile as C++ without some changes.

MSVC is probably pretty close to C99 these days. Designated initializers are C99, for example.

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Re:Ask HN: How do I learn C properly? by Leherenn on Monday March 09, 2020 @03:17AM (#22523549)

You can assign integers to enum in C++, just like in C, but not to enum class. Use the latter when you need type safety, the former when you need to easily convert integer <-> enum, which apart from (de)serialisation is rare in my experience. And even in those cases, I personally prefer the explicit casts.

As far as I know, MSVC just implements the C subset of C++.

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Re:Ask HN: How do I learn C properly? by jstimpfle on Monday March 09, 2020 @04:47AM (#22523926)

What I mean is this:

    > enum Foo { A, B, C };
    > Foo x = 1;
    test.cc:2:9: error: invalid conversion from ‘int’ to ‘Foo’ [-fpermissive]
     Foo x = 1;

I prefer not to use explicit casts because 1) using enum types is confusing to me 2) I frequently use values that are not in the enum - most often that's -1 as a way to indicate "missing". 3) I also like to iterate over all values from an enum using a plain for (int i = 0; i < NUM_FOOS; i++) without any fuss.

> As far as I know, MSVC just implements the C subset of C++.

There are things that work in MSVC C mode that do not work in C++ mode.

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