D gets the rounding right, too

[Walter Bright]

http://www.reddit.com/r/programming/comments/cb8qv/incorrectly_rounded_conversions_in_gcc_and_glibc/


0.500000000000000166533453693773481063544750213623046875
 Correct = 0x1.0000000000002p-1
 dmd =     0x1.0000000000002p-1
 strtod =  0x1.0000000000002p-1

3.518437208883201171875e13
 Correct = 0x1.0000000000002p+45
 dmd =     0x1.0000000000002p+45
 strtod =  0x1.0000000000002p+45

62.5364939768271845828
 Correct = 0x1.f44abd5aa7ca4p+5
 dmd =     0x1.f44abd5aa7ca4p+5
 strtod =  0x1.f44abd5aa7ca4p+5

8.10109172351e-10
 Correct = 0x1.bd5cbaef0fd0cp-31
 dmd =     0x1.bd5cbaef0fd0cp-31
 strtod =  0x1.bd5cbaef0fd0cp-31

1.50000000000000011102230246251565404236316680908203125
 Correct = 0x1.8p+0
 dmd =     0x1.8p+0
 strtod =  0x1.8p+0

9007199254740991.4999999999999999999999999999999995
 Correct = 0x1.fffffffffffffp+52
 dmd =     0x1.fffffffffffffp+52
 strtod =  0x1.fffffffffffffp+52

and the code:


import std.c.stdio;
import std.c.stdlib;

const NUM_CONVERT = 6;

int main ()
{
 uint i;

 char decimal[NUM_CONVERT][60] = [
  "0.500000000000000166533453693773481063544750213623046875",
  "3.518437208883201171875e13",
  "62.5364939768271845828",
  "8.10109172351e-10",
  "1.50000000000000011102230246251565404236316680908203125",
  "9007199254740991.4999999999999999999999999999999995"
 ];

 double gcc_conversion[NUM_CONVERT] = [
  0.500000000000000166533453693773481063544750213623046875,
  3.518437208883201171875e13,
  62.5364939768271845828,
  8.10109172351e-10,
  1.50000000000000011102230246251565404236316680908203125,
  9007199254740991.4999999999999999999999999999999995
 ];

 char correct[NUM_CONVERT][30] = [
  "0x1.0000000000002p-1",
  "0x1.0000000000002p+45",
  "0x1.f44abd5aa7ca4p+5",
  "0x1.bd5cbaef0fd0cp-31",
  "0x1.8p+0",
  "0x1.fffffffffffffp+52"
 ];

 for (i=0; i < NUM_CONVERT; i++)
 {
  printf ("%s\n",decimal[i].ptr);
  printf (" Correct = %s\n",correct[i].ptr);
  printf (" dmd =     %a\n",gcc_conversion[i]);
  printf (" strtod =  %a\n\n",strtod(decimal[i].ptr,null));
 }
 return 0;
}