[enriquto]

> That's true for every floating point number in every programming language you have ever used, though.

Alright, if "you" have only ever used python. In C, for example, we have hexadecimal floating point literals that represent all floats and doubles exactly (including infinities and nans that make the json parser fail miserably).

[legobmw99]

If you use the same syntax as OP, C’s parser will also round that literal. The existence of a hex literal for floats is something orthogonal

[codetrotter]

> we have hexadecimal floating point literals that represent all floats and doubles exactly

How do you do that?

A couple of resources I found but which I’m not sure if are about exactly what you speak of

https://stackoverflow.com/questions/65480947/is-ieee-754-rep...

https://gcc.gnu.org/onlinedocs/gcc/Hex-Floats.html

Furthermore, what exactly do you mean by “all floats and doubles exactly”?

[enriquto]

Yes, I was talking about what is described in your resources. You can do this:

    // define a floating-point literal in hex and print it in decimal
    float x = 0x1p-8;          // x = 1.0/256
    printf("x = %g\n", x);     // prints 0.00390625
    
    // define a floating point literal in decimal and print it in various ways
    float y = 0.3;             // non-representable, rounded to closest float
    printf("y = %g\n", y);     // 0.3 (the %g format does some heuristics)
    printf("y = %.10f\n", y);  // 0.3000000119
    printf("y = %.20f\n", y);  // 0.30000001192092895508
    printf("y = %a\n", f);     // 0x1.333334p-2

[codetrotter]

So for example if you make a variable that has the value parent commenter used

100000.000000000017

And then you print it.

Does it preserve the exact value?

[enriquto]

Your question is ambiguous for two different reasons. First, this value is not representable as a floating-point number, so there's no way that you can even store it in a float. Second, once you have a float variable, you can print it in many different ways. So, the answer to your question is, irremediably, "it depends what you mean by exact value".

If you print your variable with the %a format, then YES, the exact value is preserved and there is no loss of information. The problem is that the literal that you wrote cannot be represented exactly. But this is hardly a fault of the floats. Ints have exactly the same problem:

    int x = 2.5;   // x gets the value 2
    int y = 7/3;   // same thing

[codetrotter]

So in other words, is it fair to say that this situation is not much different from what you get with Python?