Need to remove leading zeros for floating point output

[Jerry DeLisle]

Steve Kargl wrote:
> On Fri, Oct 19, 2007 at 07:53:21PM +0000, Nick Stamatakos wrote:
>> Is there compiler option or other way to remove Leading zeros from
>> floating point fortran output?  In HP f90 FORTRAN there is an option
>> called: 
>>       +io77          Suppresses the generation of the optional leading
>>                           "0" before the decimal point for real numbers
>>                           printed with the E and F edit descriptors.
>>                           Fortran 77 suppressed these leading 
>>                           zeros unless
>>                           the NOSTANDARDIO flag was used.  Along with
>>                           +gformat77, the +io77 flag provides formatted
>>                           output compatibility with the 
>>                           Fortran 77 product.
>>
>> What is the equivalent compiler or other way to implement this option?
>> I can't find it anywhere.
>>
> 
> gfortran doesn't have an option to what you want.  You could
> however chop the leading zero with an internal write.
> 
> program a
>   character(len=20) s
>   real x
>   x = 0.1234
>   write(s,'(E12.5)') x
>   s = adjustl(s)
>   if (s(1:1) == '0') then
>      s(1:len(s)-1) = s(2:len(s))
>   end if
>   print *, x, s
> end program a
> 
> troutmask:kargl[206] gfc -o z l.f90
> troutmask:kargl[207] ./z
>   0.1234000     .12340E+00          
> 
In write_float.def, we have

   /* Output an optional leading zero.  */
   if (leadzero)
     *(out++) = '0';

leadzero is a flag telling us we have room for a leading zero.  We could add an 
option to set that byte to ' ' to suppress it.  That would not be available 
until gfortran version 4.4.  It is straightforward to do though.

Jerry

Jerry