If you’re used to coding in more modern languages, Fortran I/O can seem a little bizarre. Strings in Fortran are much more difficult to work with, since they are fixed-length rather than null-terminated. The following example illustrates a simple way to read an array of numbers from a text file when the array length is unknown at compile time.
program io_test real, dimension(:), allocatable :: x integer :: n open (unit=99, file='array.txt', status='old', action='read') read(99, *), n allocate(x(n)) read(99,*) x write(*,*) x end
Here is the text file that the array is read from. The integer on the first line is the number of elements to read from the next line.
10 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0