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?
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 
