In Fortran 90, what is a good way to write an array to a text file, row-wise?

Question

I am new to Fortran, and I would like to be able to write a two-dimensional array to a text file, in a row-wise manner (spaces between columns, and each row on its own line)

Answer 1

This may be a very roundabout and time-consuming way of doing it, but anyway... You could simply print each array element separately, using advance='no' (to suppress insertion of a newline character after what was being printed) in your write statement. Once you're done with a line you use a 'normal' write statement to get the newline character, and start again on the next line. Here's a small example:

program testing

implicit none

integer :: i, j, k

k = 1

do i=1,4
   do j=1,10
      write(*, '(I2,X)', advance='no') k
      k = k + 1
   end do
   write(*, *) ''  ! this gives you the line break
end do

end program testing

When you run this program the output is as follows:

 1  2  3  4  5  6  7  8  9 10  
11 12 13 14 15 16 17 18 19 20  
21 22 23 24 25 26 27 28 29 30  
31 32 33 34 35 36 37 38 39 40