4 ms·

C programmers are implicitly converted to the required type. Implicit conversions are one thing I don't like about C, or at least the way it ended up as int gr

• cpncrunch 4y ago
  I used to think implicit type conversions were bad in C, until I started programming in javascript.
  • kps 4y ago
    `5 - "2"` is 3, and `5 + "2"` is "52". Makes perfect sense! It could be worse, though; you could be doing Norwegian YAML.
• tialaramex 4y ago
  > I also don't like how UB turned into “a license for the compiler to undertake aggressive optimizations that are completely legal by the committee's rules, but make hash of apparently safe programs.” You can have a language where all the behaviour is defined but in my experience most programmers who whine about this in C are just as unhappy because what they actually wanted was DWIM. In a language with defined behaviour their program is wrong, which is their fault, whereas in C they can claim "obviously" it's the compiler's fault. I like it when it's my fault, I just learned something, and early in my education I assumed everybody was the same but I rapidly learned that most people prefer to be told they're correct regardless, and a language which says "Nope, 4 - 5 is a negative value and this variable in unsigned, too bad" makes those people unhappy, whereas when 4 - 5 = mysterious program behaviour they can blame the compiler engineers instead.
  • kragen 4y ago
    4u - 5u is not undefined behavior in c; unsigned arithmetic overflow is defined to wrap around, in both directions assigning -1 to an unsigned variable has never been undefined behavior either, but implementation-defined behavior (see §6.2.1.2p3 in iso c90 or §6.3.1.3 in c99 and c11); decent compilers like gcc define it to do the obviously correct thing (see https://gcc.gnu.org/onlinedocs/gcc/Integers-implementation.html https://gcc.gnu.org/onlinedocs/gcc/Integers-implementation.h...), not produce mysterious program behavior. in the new c++20 standard it's no longer even implementation-defined, but fully define behavior in the standard, but in standard c it's still implementation-defined as a programmer who whines about the kind of ub exploitation at issue here, and who (as established above) has a much clearer idea than you do of what behavior is and is not defined, specifically what i am whining about is that it's harder to debug my code if doing things like dereferencing a null pointer doesn't reliably crash it, but instead triggers the silent removal of apparently unrelated logic from my program, or subtle semantics changes in it, in the name of optimization also it sucks to have existing security-sensitive code acquire new security holes, and i don't really care if that's a learning opportunity for the guy who wrote it 20 years ago this didn't happen 20 or 30 years ago, and in those 20 or 30 years the impact of introducing fresh security holes into existing well-tested c code has greatly increased, while the usefulness of c compiler optimizations has greatly decreased
    • tialaramex 4y ago
      You're correct that 4 - 5 isn't undefined in C. But there's a good reason that Rust, for example, chooses not to make its built in integer types (either signed or unsigned) wrap on overflow. Wrapping<u32> is very easy for a typical processor to implement but in most cases overflow is a mistake, so you want to report it not silently give the wrapping answer instead when the programmer apparently hasn't considered overflow at all. If you give up the aggressive optimisations then C is even less competitive with modern languages, so you're basically arguing that it's acceptable to have code that's harder to write, more buggy and with worse performance just because that's how you'd have done it 30 years ago. At that point you're talking about a retro hobby.
      • 4y ago
• fsckboy 4y ago
  > C programmers are implicitly converted to the required type. stop trying to coerce me
  • kps 4y ago
    Consider it a promotion.
    • lelanthran 4y ago
      Or a type of pun