A problem with the readln function

Hello,

I cannot reproduce your problem here. When I run your master_ufficale.mos then I get

Mosel: E-22: I cannot open file `slave.bim' for reading (No such file or directory).

I guess this is expected, because you did not provide a slave.bim. However, this error happens a long time after the readln() calls you mentioned.

All the reading of data seems to work as expected.

What version of Mosel are you using?

Can you try to reduce your mos/txt to a minimal example that reproduces the issue?

Dear Daniel,

thank you for your kind reply.

I am copying next a reduced version of the code that does not require the bim file.

I have added a loop that prints the arrays Wcat, Ccat, L, and U.

However, if I go to the panel on the left, it looks like they have no content (please see the attached screenshot).

I am using Xpress 9.0.2 on a Windows 10 computer, while my colleague is using Xpress 8.13.

I have tried to upload both the screenshot and the reduced version of the code, but it looks like it is possible to attach just one file here, so I have to copy and paste the reduced version of the code next.

Thank you for your patience and time you are spending to help me.

Best regards,

Mauro

model ModelName

!uses "mmxprs", "mmjobs", "mmsystem";

parameters

   input="istanza_di_prova.txt"

end-parameters

declarations

Nt: integer !#type of bins

Ni: integer !#items

Nf: integer !#families

U: array(range) of integer !upper bound on the #bins of type t

L: array(range) of integer !lower bound on the #bins of type t

Nj: integer !#bins

sigma: array(range) of integer !bin j type

gamma: array(range) of integer !item i category

Ncat: array(range) of integer !#items belonging to category k

Ccat: array(range) of integer !cost of a bin of category k

Wcat: array(range) of integer !capacity of a bin of category k

C: array(range) of integer !cost of bin j

W: array(range) of integer !capacity of bin j

w: array(range) of integer !item i weight

p: array(range) of integer !p(k) profit of family k

wk: array(range) of integer !category k weight

flag: array(range) of integer !1 if item i is compulsory, 0 otherwise

family: array(range) of integer

id: integer

V: array(range) of integer !auxiliary number to count bins

Ic: set of integer

Inc: set of integer

take: array(range)of integer

epsilon: array(range) of real

best: real

Sfix: array(range) of integer

Zfix: array(range,range) of integer

comp: array(range,range) of integer !1 category k1 and k2 are compatible, 0 otherwise

fileName: string

end-declarations

fopen(input,F_INPUT)

!readln("NAME", fileName)

!readln("COMMENT")

readln("BINTYPES", Nt)

readln("ITEMS", Ni)

readln("FAMILIES", Nf)

readln("BINS_SECTION")

Nj:=0

U(0):=0

V(0):=0

forall(t in 1..Nt)do

   readln(id, Wcat(t), Ccat(t), L(t), U(t))

   Nj:=Nj+U(t)

   V(t):=V(t-1)+U(t)

end-do

writeln("Nt ", Nt)

writeln("Ni ", Ni)

writeln("Nf ", Nf)

writeln("CHECK")

forall(t in 1..Nt)do

   writeln(t, ' ', Wcat(t),' ', Ccat(t),' ', L(t),' ', U(t))

end-do

When you are working with 'readln'/'read' the contents of the file that you are reading must match exactly what you are trying to read from your Mosel model: uncommenting the lines

!readln("NAME", fileName)

!readln("COMMENT")

in your latest code example above will match the format of your input file and input values are read in correctly.

You may want to add a test after the individual read statements, such as:

procedure testread(num: integer)
  numread:=getparam("nbread")
  if numread<>num then
    writeln("Read error (expected:", num, " items read:", numread, ")")
    exit(1)
  end-if
end-procedure
 
!...
readln("FAMILIES", Nf)
testread(2)
 
readln("BINS_SECTION")
testread(1)
 
Nj:=0
U(0):=0
V(0):=0
 
forall(t in 1..Nt)do
   readln(id, Wcat(t), Ccat(t), L(t), U(t))
   testread(5)