How to Resolve Incorrect Fortran Read from Data Text File?
I Have a Text File with Two Numbers on the Same Line 108 6.7522 I Have a Fortran Subroutine Readcn That Stores the Numbers 108 6.7522 from the Text File into...
I have a text file with two numbers on the same line
108 6.7522
I have a fortran subroutine READCN that stores the numbers 108 6.7522 from the text file into the variables NN and BOX
SUBROUTINE READCN ( CNFILE, BOX )
CHARACTER CNFILE*(*)
REAL BOX
INTEGER CNUNIT
PARAMETER ( CNUNIT = 10 )
INTEGER NN
OPEN ( UNIT = CNUNIT, FILE = CNFILE, STATUS = 'OLD',
: FORM = 'UNFORMATTED' )
READ ( CNUNIT ) NN, BOX
WRITE(*,*) NN, BOX
CLOSE ( UNIT = CNUNIT )
RETURN
END
The output for READCN variables NN BOX is
3.2997999 2.74554597E-31
How do I read the values correctly?
This program is taken from
When I attempted to remove the format option in the read command this was the follow error I received
At line 686 of file MCNPT.f (unit = 10, file = 'LATTICE-256.txt')
Fortran runtime error: Missing format for FORMATTED data transfer
1 Answer
Moving from using unformatted input to formatted input requires three actions:
- changing the input to a "text file";
- opening the file for formatted, rather than unformatted, I/O;
- providing a format for the read statements.
You've done the first two of these. [If you didn't know, removing form='unformatted' means that the default of formatted I/O is used.]
All that remains is to use a format specifier in the subsequent reads. This is where the compiler is complaining.
The simplest formatted read to use is list-directed, which is given by fmt=* specifier in the read. This should be sufficient for your case, but you should ensure you are happy with its limitations.
To be precise: replace
OPEN ( UNIT = CNUNIT, FILE = CNFILE, STATUS = 'OLD',
: FORM = 'UNFORMATTED' )
READ ( CNUNIT ) NN, BOX
with
OPEN ( UNIT = CNUNIT, FILE = CNFILE, STATUS = 'OLD')
READ ( CNUNIT, * ) NN, BOX
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