[Help-glpk] If-then expression: invalid use of reserved keyword if

[Kasper Tordrup]

Hi guys

I was trying to make a simple if-then statement as below, but failed with the error: "invalid use of reserved keyword if".
I then tried searching the archive but the closest I got to an answer, was that it is not allowed to use if-then like this.
Anyone know a workaround for that?
I got a lot of 0-entries in 'x' and i simply just want to print the ones that is set to 1

for {r in R} {
 for {s in S} {
  for {i in 1..fr[r]} {
   if x[s,r,i] = 1 then printf "x[%s,%s,%i] = %i\n", s,r,i,x[s,r,i]
  }
 }
}

Best regards,
Kasper