Read/Write Binary

[cosmoh2o]

Please help,

I am new to Fortran so this is probably a VERY simple question but what is the easiest way to write data to a binary file using Fortran?

Any help/hint/simple example code would be wonderful.

Thank you.

 

[xwb]

First open the file for an unformatted file with record length of 1.

          open (
     &        unit = fhand,  ! fhand is an integer set to a value
     &        file = iFilename,
     &        status = 'UNKNOWN',
     &        access = 'DIRECT', ! Otherwise it assumes a record header
     &        form = 'UNFORMATTED',
     &        recl = 1,
     &        err = 100) ! 100 is a label which tells you an error has occurred

When writing, indicate the record position

      write (fHand, rec=1) bfType, bfSize, bfReserved, bfOffBits

Last, close the file

      close (fHand)

On some implementations, a record length of 1 is not allowed. The minimum is probably 4. In that case rec=2 writes to byte 5 to 8.

You also have to watch out for the big endian little endian problem. In layman's terms, byte swapping. For instance, on some machines 513 is stored as 0201 hex, on other machines it is stored as 0102 hex. On machines where it is stored as 0102, the machine swaps them back to 0201 during processing.

 

[cosmoh2o]

Thank you xwb.