Suggestions on mimicing fgetc and fseek with F90

Hi all,

I know that many compilers have hooks to the C routines fgetc and fseek. I' However, I was hoping to use standard F90 I/O to do this. I read data files that vary from 3MB to 45MB in size. So sometime the whole file is read to access data. Other times I seek into the file to pluck a few bytes out.

Would something like the following be practical

To mimic reading a file in a fgetc fashion

character(1) c1
character(100) text100
open(iunit, fname='foo', form='formatted',access='sequential')

do i =1,100
  read(iunit,'(A1)',advance='no')c1
  text100(i:i) = c1
end do


The to do a seek followed by a read I was thinking of something like the following that would read characters starting at the 300th character and stopping at the 399th character.

character(1) c1
character(100) text100
open(iunit, fname='foo', form='formatted',access='direct',recl=1)

j = 1
do i =300,399
  read(iunit,rec=i)c1
  text100(j:j) = c1
  j = j +1
end do


Does this seem like a reasonable approach? Are there any known speed issues with this approach? Fgetc and fseek are working for me now, but I would like to removed the non-standard fortran calls.

Thanks in advance,

Mike Sutton

.

Relevant Pages

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