[Mingw-notify] [ mingw-Bugs-2136252 ] c99, printf and float zero precision

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Bugs item #2136252, was opened at 2008-09-29 18:23
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Roumen Petrov (rumen)
Assigned to: Nobody/Anonymous (nobody)
Summary: c99, printf and float zero precision

Initial Comment:
The test program:
#include <stdio.h>

int main () {
  float f = 0.003;
  printf("%.*f\n", -1, f);
  printf("%.*f\n",  1, f);
  printf("%.*f\n",  0, f);
  printf("%.f\n"  , f);
  printf("%.0f\n" , f);
  printf("%#.0f\n", f);

  printf("%.*a\n", -1, f);
  printf("%.*a\n",  1, f);
  printf("%.*a\n",  0, f);
  printf("%.a\n"  , f);
  printf("%.0a\n" , f);
  printf("%#.0a\n", f);

  printf("%a\n", 30.0)  ;
  printf("%A\n", 30.0)  ;
  printf("%.2a\n", 30.0);
  printf("%.2A\n", 30.0);  
  return(0);
}

This program is compiled with following options:
1) -posix -lmingwex
2) without options run on os with msvcrt 7.0x
3) -specs=msvcr90 (as is described in wiki to link with msvcr90)

On the first group of test the output is (/ separate results):
0.003000  (same in all cases )

0.0 (same in all cases )

0. / 0 / 0

0. / 0 / 0

0. / 0 / 0

0. (same in all cases )

Mingw output extra dot and it seems to me that this is not compatible with c99.

The second group of the test 
0x1.89374cp-9 / a / 0x1.89374cp-9

0xc.5p-12 / a /0x1.9p-9

0xcp-12 / a / 0x1p-9

0xcp-12 / a / 0x1p-9

0xcp-12 / a / 0x1p-9

0xc.p-12 / a / 0x1.p-9
Ms
vcrt 7.0 don't know %a format specifier. No idea what is correct output for c99 standard, but dot in output looks good.


The third group:
0x1.ep+4 / a / 
0x1.e00000p+4
0X1.EP+4 / a / 
0X1.E00000P+4
0xf.00p+1 / a / 
0x1.e0p+4
0XF.00P+1 / a / 0X1.E0P+4
I think that mingw and msvcr90 fail on zero precision output(%a). The expected result is 0xfp+1.
On the "%.2a" mingw looks good, msvcr90 fail.

The question is whether mingwex output (rt version 3.15) is correct in first and third cases ?
What is expected output for the second case ?

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