Handling big FP numbers

[Dennis]

On Sunday, 10 February 2019 at 20:25:02 UTC, Murilo wrote:
> It seems this is a feature of D I will have to get used to and 
> accept the fact I can't always get the same number as in C

What compilers and settings do you use? What you're actually 
comparing here are different implementations of the C runtime 
library.

```
#include<stdio.h>

int main() {
	double a = 99999912343000007654329925.7865;
	printf("%f\n", a);
	return 0;
}
```

I compiled this with different C compilers on Windows 10 and 
found:

DMC:   99999912342999999472000000.000000
GCC:   99999912342999999000000000.000000
CLANG: 99999912342999999470108672.000000

As for D:
```
import core.stdc.stdio: printf;

int main() {
	double a = 99999912343000007654329925.7865;
	printf("%f\n", a);
	return 0;
}
```

DMD: 99999912342999999472000000.000000
LDC: 99999912342999999470108672.000000

DMC and DMD both use the Digital Mars runtime by default. I think 
CLANG and LDC use the static libcmt by default while GCC uses the 
dynamic msvcrt.dll (not sure about the exact one, but evidently 
it's different). So it really hasn't anything to do with D vs. C 
but rather what C runtime you use.