' a program to show how the Chain command can be used.
' We rely on MMBasic initialising numeric variables to 0.
' Each chained program increments the value of counter
' that tracks where we are up to.
' If we initialised the counter to 0 in code, it will continually
' get reset and overwrite the values updated by the chained programs.

? "UpTo counter is:"; UpTo

If UpTo = 0 then

[2 lines added]
OPTION Base 1 ' must be set before any DIM statements
False = 0 : True = 1 ' if done here, only performed once.

CHAIN "Chain0.bas"

ElseIf UpTo = 1 then
CHAIN "Chain1.bas"

Elseif UpTo = 2 then
CHAIN "Chain2.bas"

Else
? "Finished"
endif

' Chain0.bas

? "In Chain0.bas"
UpTo = UpTo + 1
CHAIN "chn-demo.bas" ' back to calling program
END

' Chain1.bas

? "In Chain1.bas"
UpTo = UpTo + 1
CHAIN "chn-demo.bas" ' back to calling program
END

' Chain2.bas

? "In Chain2.bas"
UpTo = UpTo + 1
CHAIN "chn-demo.bas" ' back to calling program
END

' this program demonstrates a possible bug in the chain command.
' The pointer that tracks the next DATA element to be read
' causes unexpected results when the CHAIN command is used.
'
DIM ARR1$(6)
DATA "Data1", "Data2", "Data3", "Data4", "Data5", "Data6"

For i = 1 to 4 ' only 4 of the 6 in this test
Read ARR1$(i)
PRINT "Main program saved value "; ARR1$(i)
next i

CHAIN "TestChn.bas"

' Part 2 of a program to demonstrate a potential bug with the CHAIN command.
'
DIM ARR2$(6)
DATA "P2Data1", "P2Data2", "P2Data3", "P2Data4", "P2Data5", "P2Data6"

For i = 1 to 6
Read ARR2$(i)
PRINT "Chained program saved value "; ARR2$(i)
next i

END

'Chain1.bas
Fname$="Chain2.bas"
a=10
Dim d(a)
for i=1 to a
d(i)=i
next
i=1
Main(a)
Chain Fname$
End

Sub Main(c)
Local b,c$,e(c),i
for i=1 to c
e(i)=i
Next
c=c+2
b=c
C$="Now is the time"
d$=c$
End Sub

'Chain2.bas
Print "Fname$=",Fname$
Print "a=",a
Print "b=",b
Print "c=",c
Print "c$=",c$
Print "d$=",d$
Print "i=",i
Print "Array d=";
For j=1 to 10
Print d(j);
Next
Print
For j=1 to 10
Print e(j)
Next