What one change in C would make it a better language for you?

A very surface change (almost syntactic sugar) that would be neat for me is some form of generics. Specifically, to allow me to implement an algorithm once for different data types. Right now I do it with preprocessor macros and includes; it works but feels wrong.

Going deeper, but not as far as changing the language (not hoping for memory safety here), I would like better research and documentation for undefined behavior (UB).

I'm not completely opposed to UB. I understand it is an unfortunate performance/safety trade-off that's not fully avoidable in a historical language like C. However, there are many types of UB, and for a few of them, the performance benefits feel theoretical (not supported by empirical evidence). I would love some before/after benchmarks with the types of UB that can be disabled in the compiler, and some open-minded discussion afterwards.

Bounds checks on arrays/strings. This would prevent the largest class of errors (buffer overflows) seen in C code.

I'm not sure if that horse could ever be put back in the barn, but I think my mindset for using C would probably feel a lot different if somehow it could be made a strict subset of C++.

The default behavior for a case within a switch statement should be to break. If you want to fall through to the next case, it should have been an explicit command (e.g. fallthrough).

switch(x) { case 1: DoSomething(); case 2: DoSomethingElse(); case 3: SomePrep(); fallthrough; case 4: DoMore(); default: DoNothing; }

Only one statement needed to have case 3 fall through to case 4. No breaks needed at the end of any other cases.

It's not just one, but a short list

  get rid of Macros
  adopt Pascal style pointer references...   @ is an address,   p^ is what p points to
  adopt some form of counted strings, with a null on the end for compatibility
  adopt Pascal style cast statements, with each path being exclusive (default break)

If the brain-dead implicit type promotion rules were removed. E.g

    unsigned int a = 5;
    signed int b = -10;
    bool c = a + b > 0;

c is true.

Modules. No more duplicating code into header files, just import a module like in modern languages. I love C but really hate headers.

Then, second for namespaces.

Namespaces.

Defer (which also means lambdas). I really hope that the proposal gets in the next standard.

"case" variable scope

deprecate headers

I ;

don't;

know;