value from a sub program

[Walter VanDerwall]

Hello

I'm trying to get a value back from a sub program (nme$). I compile the sub program (pbc -cu inputit), which creates inputit.pbu
I then compile the main program pbc test


When the main program prints nme$ its always empty.

What am i doing wrong?
Thanks



main program (test):
100 link$ "inputit.pbu"
110 declare sub inputit(single, single single)
120 call inputit(25,10,20)
130 print nme$
140 end


sub program (inputit):
100 sub inputit(lgth,row,col) public
110 blah blah blah
120 nme$="hello world"
130 end sub

[Michael Mattias]

To return a value from a procedure in a PBU unit file, you can either pass the variable as a parameter....

  DECLARE SUB inputIt (single, single, single, String)  

  CALL Inputit (25, 10, 20,nme$) 
  Print nme$

SUB InputIt (l, r, c, N$) Public 
    ....
    N$ =  "hello world"

.. or make the called procedure a FUNCTION returning that value ...

  DECLARE FUNCTION inputIt (single, single, single) AS STRING 
  Nme$ = Inputit (25, 10, 20) 
  Print nme$

FUNCTION InputIt (l, r, c) Public AS STRING 

     FUNCTION =  "Hello World"
    ....

.. or use EXTERNAL variables, but that is IMO poor practice so I'm not going to show you that.

MCM

[Mike Luther]

More power, but ....

You can also use string arrays as in:

RDIM% = 75
DIM X$(-RDIM% TO +RDIM%)

DECLARE SUB inputIt (single, single, X$())

Yes! Minus to plus values in a variable length string
array. Why that? Well rolling the positive content items
into the negative content section of the allocated memory
is a wonderful way to interface two complete mixes of what
will be eventually in the 'normal' X$() collection we think about as programmers, from a dual logic major file
operations code work.

Slush the as now data. Romp the new data into the old
place in memory. Operate for comparative and finalization
on the compare/contrast between the positive and negative exact logic in the master array, for the final new data!

But I warn you, if you ever have to think about portability for PowerBasic to C or C++ code which thinks
about what we know as simple strings - as character arrays, and then go toward variable length such character
arrays forward into object programming in C/C++, you are in for a lot of head scratching. To say nothing if your
priceless efficient PB code is using X$(-50 TO +50) type memory management design.

[Michael Mattias]

Mike, Mike, Mike..... keeping track of the subscripts or testing if positive or negative is so, so, well, Philistine.....

 

   REDIM  MyArray (any) 
  ' fill it with all kinds of disparate stuff with "like items" in consecutive element numbers
  ' --------------------------------------------------------   
  ' Pass only subscripts  8  thru 16  to a procedure
 ' ---------------------------------------------------------  
   REDIM WorkArray (8) AT VARPTR(MyArray(8))   ' nine elements starting with subscript 8 
  CALL  InterestedFunction ( WorkArray()) 

FUNCTION InterestedFunction ( W() AS <datatype>) AS something 

   FOR Z = LBOUND (W,1) TO UBOUND (W,1) 
     ' processing here:elements 8 thru 16 of original array 
   NEXT
  ....

No muss, no fuss, no bother.... PLUS you earn seven (7) panache points! Such a Deal!

MCM