Re: format with G descriptor


"Roman" <shekht@xxxxxxxxxx> wrote in message news:e7ee8bdf-697a-4298-9808-3d45d580f6aa@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx


2 format(g)

s = "1.0"

read(s,*) r
write(*,*) r ! output: 1.000000

read(s,2) r
write(*,*) r ! output: 1.000000


s = "1"

read(s,*) r
write(*,*) r ! output: 1.000000

read(s,2) r
write(*,*) r ! output: 1.0000000E-07 !!!!!!!

stop
end program test_format_G
!-------------------------------------------

What happens when you don't obey to the standard depends on the compiler.
Try e.g with "g10.0" and it will work - or way not with "read(s,*) r" if you are using Fortran 90/95 or later,

Cut from one manual:

The full descripor is: Gw.d[Ee] where

w is the field width
m is the minimum number of digits that must be in the field (including zeros).
d is the number of digits to the right of the decimal point
E is the exponent field
e is the number of digits in the exponent
Rules for Input Processing

On input, the G data edit descriptor transfers w characters from an external field and assigns their real value to the corresponding I/O list item. The G descriptor interprets and assigns input data in the same way as the F data edit descriptor.

Rules for Input Processing

On input, the F data edit descriptor transfers w characters from an external field and assigns their real value to the corresponding I/O list item. The external field data must be an integer or real constant.

If the input field contains only an exponent letter or decimal point, it is treated as a zero value.

If the input field does not contain a decimal point or an exponent, it is treated as a real number of w digits, with d digits to the right of the decimal point. (Leading zeros are added, if necessary.)

If the input field contains a decimal point, the location of that decimal point overrides the location specified by the F descriptor.

If the field contains an exponent, that exponent is used to establish the magnitude of the value before it is assigned to the list element.What a compiler does if you don't follow this might be whatever it likes!

Kurt

.

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