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Comment by tredre3 | Hacker News Reader

> In Rust we'd use `const` for this but in C you need to use the C pre-processor language instead to make constants, which is kinda wild.

I get that you're not very familiar with C? Because in C we'd use const as well.

    const int x = 2;
    x = 3; // error: assignment of read-only variable 'x'

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That's not a constant, that's an immutable variable which is why your diagnostic said it was read-only.

   const int x = 2;
   int *p = &x;
   *p = 3; // Now x is 3

And since I paid for the place where I'm writing this with cash earned writing C a decade or so ago, I think we can rule out "unfamiliar with C" as a symptom.

Now x is 3 but you also get a compiler warning telling you not to do that.

In my opinion it's a bit disingenuous to argue that it isn't a const just because you can ignore the compiler and shoot yourself in the foot. If you listen to the compiler, it is reflected in the assembly that it is a constant value the same as #define x 2.

Is Rust better at enforcing guarantees? Of course. Is `const` in C `const` if you don't ignore compiler warnings and errors? Also of course.

> And since I paid for the place where I'm writing this with cash earned writing C a decade or so ago

Ditto!

Perhaps they’re conflating how you can’t use “const” as a compile time constant (e.g., you can’t declare the size of an array with a “const” variable). If so, C23 solves this by finally getting the constexpr keyword from c++

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