On Friday, 25 October 2019 at 06:53:38 UTC, berni44 wrote:
On Thursday, 24 October 2019 at 20:48:02 UTC, Yui Hosaka wrote:
Do you have any idea for this issue?
I added a bug report:
https://issues.dlang.org/show_bug.cgi?id=20320
Internally the conversation from the binary representation of
the value to the printed one is done by a call to a C function
called snprintf. Probably the error is inside of this function
call. But it could also happen before. Maybe the internal
representation of 0.016 is allready wrong.
It would be helpful if you could run the following program and
post the output:
import std.stdio;
import std.format;
void main()
{
real b = 0.016;
writefln!"%.2f"(b);
foreach (c;format("%r",b)) writef("%x ",c);
writeln();
char[6] sprintfSpec = "%*.*Lf";
char[512] buf = void;
import core.stdc.stdio : snprintf;
immutable n = snprintf(buf.ptr, buf.length,
sprintfSpec.ptr, 0, 2, b);
writeln(buf[0..n]);
}
Thank you for forwarding the issues.
The outputs for your program are as follows:
Without compiler options (32-bit):
---
0.01
3b df 4f 8d 97 6e 12 83 f9 3f
0.01
---
and some trailing characters. "./a | od -c" shows:
---
0000000 0 . 0 1 \r \n 3 b d f 4 f
8
0000020 d 9 7 6 e 1 2 8 3
f 9
0000040 3 f \r \n 0 . 0 1 377 377 206 003
\r \n
0000060
---
With "-O" (32-bit), the output changes in every run, such as:
---
0.01
3b df 4f 8d 97 6e 12 83 f9 3f
0.01S
---
0.01
3b df 4f 8d 97 6e 12 83 f9 3f
0.01b
---
0.01
3b df 4f 8d 97 6e 12 83 f9 3f
0.01c
---
With "-m64" or "-m64 -O":
---
0.02
3b df 4f 8d 97 6e 12 83 f9 3f
0.00
---
