You have not seen it because it's new in the F2008 draft. In F95 (and
maybe F90) the G format can be used with any intrinsic type for input or
output. But through F2003, it requires that you specify a width for all
types. There was a desire to allow reals and complexes to be output
with "minimal" width as one can for integers with I0.
As it was explained to me, there had been a proposal to add some sort of
CSV-like formatting to Fortran to provide for data interchange. That
got shot down, but in its place two items did make it in to the F08
draft: G0 and "unlimited format items". G0 is along the lines of I0 in
that the "processor" determines the width for the output value. While
the standard does not say so explicitly, the expectation is that this
will be the minimum width necessary to represent the value. G0 does
this for all types, not just integers. G0 is allowed for output only,
not input.
The comment you refer to said that G0 was less useful because it did not
allow the minimum number of digits to be specified for real and complex
values. J3 agreed and amended the text to allow "d" to be specified on
output.
The notion was that with G0 and the unlimited format item (this allows
you to use * as the repeat count for a format group) you could have a
truly generalized output format for arbitrary data.
--
Steve Lionel
Developer Products Division
Intel Corporation
Nashua, NH
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