SPLIT subroutine

This module is part of the original MMBasic library. It is reproduced here with kind permission of Hugh Buckle and Geoff Graham. Be aware it may reference functionality which has changed or is deprecated in the latest versions of MMBasic.¶

  ' Subroutine to split a delimited string of characters into individual
  ' substrings and return those substrings in a string array.
  ' As you can't pass arrays in MM Basic, the returned array will always
  ' be named splitup$()
  ' The program automatically calculates the number of substrings in the string
  ' and the size of the largest substring, then scales the array accordingly.
  ' The number of substrings is returned in array position 0 and the maximum
  ' length of each substring is returned in array position 1
  
  Print "Testing code for split$ subroutine"
  Print
  Print "Test string is  'abc,defg,hijkl,+123.678,-5' with comma delimiter"
  a$="abc,defg,hijkl,+123.678,-5"
  Print "Usage is  SPLIT$ arg$,delimiter$"
  
  split$ a$,","
  
  Print "The splitup array that is created is a one dimensional array that is "
  Print "the number of substrings in the argument string + 2 in depth, "
  Print "each of which equals the largest substring in characters long"
  Print "Splitup$(0) has the number of substrings extracted in it"
  Print "Splitup$(1) is the maximum string length of any substring"
  Print "Splitup$(2) through Splitup$(n) contain the delimited substrings"
  Print " of the argument string"
  Print
  Print "Test run"
  Print "First substring of argument string at position 2 is ",splitup$(2)
  Print "Second substring of argument string at position 3 is ",splitup$(3)
  Print "Third substring of argument string at position 4 is ",splitup$(4)
  Print "Fourth substring of argument string at position 5 is ",splitup$(5)
  Print "Fifth substring of argument string at position 6 is ",splitup$(6)
  ' End of test code
  
  ' SPLIT subroutine
Sub split$(arg1$,arg2$)
  ' arg1$ is the string to be split
  ' arg2$ is the delimiter to split on
  Local whole$,delim$
  Local numels,maxlen,wholelen,ellen
  whole$=arg1$
  delim$=arg2$
  If Instr(whole$,delim$) <> 0 Then
    numels = 1                         ' delimiter found
    maxlen = 1
    Do While Instr(whole$,delim$) <> 0 ' now count up elements
      ellen = Instr(whole$,delim$)-1   ' and maximum size so we
      If ellen > maxlen Then
        maxlen = ellen                 ' can dimension array
      EndIf
      numels = numels + 1
      wholelen = Len(whole$)
      whole$ = Right$(whole$,wholelen-(ellen + 1))
    Loop
    If Len(whole$) > maxlen Then
      maxlen = Len(whole$)
    EndIf
    
    whole$ = arg1$
    Erase Splitup$
    Dim splitup$(numels+2) length maxlen
    splitup$(0) = Str$(numels)
    splitup$(1) = Str$(maxlen)
    For x = 2 To numels+1
      wholelen = Len(whole$)
      If x = numels+1 Then
        ellen = Len(whole$)
        splitup$(x) = whole$
      Else
        ellen = Instr(whole$,delim$) - 1
        splitup$(x)=Left$(whole$,ellen)
        whole$ = Right$(whole$,wholelen-(ellen+1))
      EndIf
    Next x
  Else
    Print "Error: No delimiter in string"
  EndIf
End Sub