Conversation

Notices

1. Embed this notice
   lfa (lfa@hostux.social)'s status on Friday, 15-Nov-2024 04:13:27 JST lfa

   Why so many people hate C?
   Because the C language assumes you know what you’re doing and lets you. If you don't know what you are doing you can learn or you can hate the language.

   #clanguage #c #programming

   • Embed this notice
     lfa (lfa@hostux.social)'s status on Saturday, 16-Nov-2024 01:55:00 JST lfa

     in reply to

     • Panicz Maciej Godek

     @PaniczGodek This is the part: " the C language assumes you know what you’re doing" 😉

     An int overflow is something common to almost any language as far as I know, and the implicit conversions are documented in the C Standard.

   • Embed this notice
     Panicz Maciej Godek (paniczgodek@functional.cafe)'s status on Saturday, 16-Nov-2024 01:55:01 JST Panicz Maciej Godek

     in reply to

     @lfa

     other than that (and silent implicit conversions), C has its charm

     Now, C++ - what an abomination!

   • Embed this notice
     Panicz Maciej Godek (paniczgodek@functional.cafe)'s status on Saturday, 16-Nov-2024 01:55:02 JST Panicz Maciej Godek

     in reply to

     @lfa

     char c = 0x80;
     if (c == 0x80) {
     puts("C is OK");
     }
     else {
     puts("there's something wrong with C");
     }

   • Embed this notice
     lfa (lfa@hostux.social)'s status on Saturday, 16-Nov-2024 01:56:28 JST lfa

     in reply to

     • Uli Kusterer (Not a kitteh)

     @uliwitness I'm not saying C is an easy language nor I'm saying everyone has to use it 😉

   • Embed this notice
     Uli Kusterer (Not a kitteh) (uliwitness@chaos.social)'s status on Saturday, 16-Nov-2024 01:56:30 JST Uli Kusterer (Not a kitteh)

     in reply to

     @lfa Or maybe life is too short to use a language that has so many wrong defaults, undefined/implementation-defined behaviors etc., when, instead of trying to remember all the things you shouldn’t do, you could just use a language that does the right thing by default, freeing your brain up to actually design and plan the parts that make your program special.

     Maybe I'll finally know what I'm doing and will learn after another 29 years of writing C.

   • Embed this notice
     lfa (lfa@hostux.social)'s status on Saturday, 16-Nov-2024 02:18:39 JST lfa

     in reply to

     • Panicz Maciej Godek

     @PaniczGodek Some conversions are implementation dependent not all of them.

   • Embed this notice
     Panicz Maciej Godek (paniczgodek@functional.cafe)'s status on Saturday, 16-Nov-2024 02:18:40 JST Panicz Maciej Godek

     in reply to

     @lfa no it doesn't. It is implementation-dependent.

   • Embed this notice
     lfa (lfa@hostux.social)'s status on Saturday, 16-Nov-2024 02:57:58 JST lfa

     in reply to

     • Panicz Maciej Godek

     @PaniczGodek Sorry I thought you where talking about the conversions.

     Your sample of the int overflow is going to get caught if you set the warning flags of the compiler, and because your affirmation sounded odd to me, I tested your sample on GNU/Linux with GCC 12 and on OpenBSD with clang 16 and I got exactly the same result.

   • Embed this notice
     Panicz Maciej Godek (paniczgodek@functional.cafe)'s status on Saturday, 16-Nov-2024 02:57:59 JST Panicz Maciej Godek

     in reply to

     @lfa what does int overflow have to do with that?

   • Embed this notice
     pinskia (pinskia@hachyderm.io)'s status on Saturday, 16-Nov-2024 03:05:22 JST pinskia

     in reply to

     • Panicz Maciej Godek

     @PaniczGodek @lfa oh yes the implicit conversion to int. It is even worse if you do: '\0x80' as in C++ it would the char type while in C it is still int.
     Oh and is char signed or unsigned depends on the target.

   • Embed this notice
     lfa (lfa@hostux.social)'s status on Saturday, 16-Nov-2024 03:17:51 JST lfa

     in reply to

     • Panicz Maciej Godek

     @PaniczGodek because char, unsigned char and signed char are integer types.

     A char can contain a value from -128 up to 127. 0x80 is 128 so when you set 0x80 to a char variable it's going to overflow. That's why your if fails because you are comparing if your char is 128 and it's not.

     If you use an unsigned char which can hold values from 0 to 255 then your if is going to work as expected.

   • Embed this notice
     Panicz Maciej Godek (paniczgodek@functional.cafe)'s status on Saturday, 16-Nov-2024 03:17:52 JST Panicz Maciej Godek

     in reply to

     @lfa but I still don't get what this has to do with int overflow

   • Embed this notice
     Panicz Maciej Godek (paniczgodek@functional.cafe)'s status on Saturday, 16-Nov-2024 03:17:53 JST Panicz Maciej Godek

     in reply to

     @lfa (but I trust that they both conform to the C language specification)

   • Embed this notice
     Panicz Maciej Godek (paniczgodek@functional.cafe)'s status on Saturday, 16-Nov-2024 03:17:54 JST Panicz Maciej Godek

     in reply to

     @lfa I tested here https://www.onlinegdb.com/8ejcl5Le9A (gcc 11.4.0) and on clang 16.0.4, and only clang behaved sanely.

   • Embed this notice
     lfa (lfa@hostux.social)'s status on Saturday, 16-Nov-2024 03:53:45 JST lfa

     in reply to

     • Panicz Maciej Godek

     @PaniczGodek you're right it's a conversion I mixed concepts sorry.

   • Embed this notice
     Panicz Maciej Godek (paniczgodek@functional.cafe)'s status on Saturday, 16-Nov-2024 03:53:46 JST Panicz Maciej Godek

     in reply to

     @lfa Overflow is something that happens during arithmetic operations. When I set 0x80 to a char variable (assuming it's at least 8-bit wide), that variable contains exactly this value: 0x80 (or bit pattern 0b10000000). There is no overflow.

     The problem arises with the operator ==, which performs a widening conversion of the variable to the "int" type, because it treats that variable as a signed value (which is implementation-dependent, which is a problem on its own), and instead of treating it as 0x80, it treats it as 0xFF80 (on 16-bit platforms) or 0xFFFFFF80 (on 32-bit platforms), because this is how widening conversion with 2's complement number representation works.