Fortran not writing to screen while file is open - fortran

Question

Context: I have the intention to put a certain Fortran subroutine to some tests to see what is wrong with it. It's a numerical simulation and the results are not matching with theory. I use the write statement to do some simple debugging.
The problem: While a file is open in my main routine, I can't seem to write anything to the screen (so I can't check which stuff are being incorrectly passed to a certain chain of subroutines and etc.). It writes all fine when I do it before opening the file, but not inside it (after opening and after closing it).
Here is the code I'm referring to:
WRITE(*,*) 'BLA !<---------------------------------------
WRITE(*,*) 'BLA BLA' !<---------------------------------------
do p=1,N !open files
write(posvel, "(a,i0,a)") "1Dposveldatacomelasticaxy1", p, ".dat"
OPEN(unit=p, file=trim(posvel), status="unknown")
end do
WRITE(*,*) 'bla' !<---------------------------------------
t = tmin
cont = 0
do while ((t + dt) < (tmax))
t = t+dt
cont = cont+1
do i = 1, N
forcax(i) = 0.0d0
forcay(i) = flagy(i)*gravidade(m(i))
do j = 1, N
call coefficients(m(i), m(j), gama_n, k_n)
Fx_elastica(j,i) = 0.0d0
Fy_elastica(j,i) = 0.0d0
Fx_viscosa(j,i) = 0.0d0
Fy_viscosa(j,i) = 0.0d0
WRITE(*,*) 'inside j loop' !<---------------------------------------
if (i .NE. j) then
if ( (abs(sqrt(((xold(i)-xold(j))**2)+(yold(i)-yold(j))**2))).LE. (a(i)+a(j)) ) then
WRITE(*,*) 'inside collision' !<---------------------------------------
call forca_elastica(k_n, a(i), a(j), xold(i), xold(j), yold(i), yold(j), Fx_elastica(j,i),&
Fy_elastica(j,i))
if (Fx_elastica(j,i) .GT. 0.0d0) then
Fx_elastica(i,j) = -Fx_elastica(j,i)
WRITE(*,*) 'elastic x is being passed' !<---------------------------------------
end if
if (Fy_elastica(j,i) .GT. 0.0d0) then
Fy_elastica(i,j) = -Fy_elastica(j,i)
WRITE(*,*) 'elastic y is being passed' !<---------------------------------------
end if
forcax(i) = forcax(i) + flagex(i)*Fx_elastica(j,i)
forcay(i) = forcay(i) + flagey(i)*Fy_elastica(j,i)
end do
call integracao_Euler_xy (xold(i),xnew(i),vxold(i),vxnew(i),forcax(i),yold(i),ynew(i),vyold(i),vynew(i),forcay(i),m(i))
if (mod (cont,5000).eq. 0) then
WRITE(p, *) int(cont/5000), t, xold(i), yold(i), forcax(i), forcay(i) !<---------------------------------------
end if
end do
end do
do p = 1,N !close files
close(unit=p)
end do
Just look at the WRITE statements. The first two appear on the screen alright. After OPENing the files, though... It doesn't. The WRITE statements that depend on conditions are the ones I want to see, but Fortran is not even writing the ones that don't depend on those conditions. Also, take a look at the last WRITE statement - it writes to the file with no problems.
Any ideas on how to fix/contour this problem?
I'm using Fortran 90.

Answer 1

You should not use small numbers for unit numbers. You are looping from 1 with a step of 1. You are almost guaranteed to hit the pre-connected units for standard output and standard input. See also Standard input and output units in Fortran 90?
Loop from some larger number, say from 100, or use newunit= and store the unit numbers in some array.
Also note that p has value N+1 at WRITE(p, *) ....