I am trying to copy the code from a QBasic tutorial, but I keep getting a weird thing.
The code I am trying to copy is:

DIM SHARED room%
INPUT "What now?"; Answer$
Temp% = 0
IF Answer$ = "" THEN A$ = ""; EXIT SUB

but the second I try to enter the last line, DOSBOX or QBasic changes it to

EXIT DEF

What do I do? (The tutorial is about how to build a parser for a text adventure, BTW).