FORTRAN 90 Open file issues - file-io

Question

I've been searching around this code for long now and can't seem to find the reason of this not working... Maybe an outsiders view can help.
!I open File 1
!Opening File 1
open(2, File='File1.txt',status='old')
read(2,*)!File 1 header
PRINT*,'File1.txt read'
!Read it
DO b=1,nb
DO i=1,ni(b)
READ(2,*)dum(b,i),Qr(1,xbu(b),i),hr(1,xbu(b),i),Ar(1,xbu(b),i),Pr(1,xbu(b),i),dx(xbu(b),i),sx(xbu(b),i)
END DO
END DO
And it's fine. I've printed it, it's all there. But when i go to File 2, doing the exact same thing:
PRINT*,'Reading File 2 '
open(3, File='File2.txt',status='old') !<- It stays here forever.
PRINT*,'File2.txt read'
The files are plain txt, with real values like this
File 1:
11 0 0 0 0 6500 1.2
File 2
11 0.00 0.00 0.00 0.0
Any thoughts on what could cause the same code to fail the second time?

Answer 1

You should probably throw some error checking in there, try putting
open(3, File='File2.txt',status='old',iostat=io_status, err=100)
And somewhere put
100 write(*,*) 'io status = ', io_status
stop
I also recommend writing a function which checks for the first available fortran unit number rather than hard coding it in, something like getting free unit number in fortran