Any limits to string literals using the _ (line continuation)?

[Bern Ertl]

I'm developing a rather long SQL instruction set to create some tables for a database. Is there a limit to the size of a string literal that I can code using the underscore for line continuation?

[Bob Zale]

255 characters.

[Michael Mattias]

255 may be PER LINE

By concatenating, it's essentially limitless as far as I can tell ..

   CreateStmt  =  "CREATE TABLE  foo  (" _ 
                       &  "col1 NUMBER (12,0), " _ 
                       &  "col2 TIMESTAMP, " _ 
                       &  "col3 VARCHAR2(60), " _ 
                       &  .....
                       & "lastcol INTEGER ) "

MCM

[Bern Ertl]

Thanks Bob, I just got a compile time error for too long/complex of a MACRO which consists of trying to execute my SQL statement.

I did mean string literal, not string equate. The compiler complained on line 32 of my (currently) 37 line statement. I'm fairly certain it's more than just 255 characters.

Anyway, what is the best way to handle this situation? I have a known/predefined large string that I need to pass as a parameter to a function.

[Kev Peel]

Use a string resource

[Michael Mattias]

// myprog.rc 
101    RCDATA 
BEGIN 
     "create table foo  (", 
     " col1 number(12,0),", 
      "col2 TIMESTAMP,",  
      ...,             ///  TRAILING COMMA EACH LINE IMPORTANT!
     " lastcol INTEGER)" 
END

[Michael Mattias]

DATA  "Create Table foo (col1 NUMBER (12,0), col2 VARCHAR(64)," 
DATA  "col3 TIMESTAMP," 
DATA  "coln datatype (params), ...
DATA  ...
DATA  "lastcol  BLOB)" 

  CreateStmt = READ$(1) & READ$(2).....

[Fred Harris]

I've always wondered about that too Bern, because Visual Basic would only allow me to go ten or twelve lines or something like that. Where I run into it is with SQL statements, which I like to format like so...

szCreate= _
  "CREATE TABLE Main " & _
  "(" & _
    "Dist         int            NOT NULL," & _
    "Yr           int            NOT NULL," & _
    "Num          int            NOT NULL," & _
    "Type         int            NOT NULL," & _
    "BF           int                NULL," & _
    "ValBF        money              NULL," & _
    "Hcf          int                NULL," & _
    "ValHcf       money              NULL," & _
    "Acres        int                NULL," & _
    "minBid       money              NULL," & _
    "rdCost       money              NULL," & _
    "dtOpen       smalldatetime      NULL," & _
    "dtExpir      smalldatetime      NULL," & _
    "nBids        int                NULL," & _
    "bidPrice     money              NULL," & _
    "strBuyer     nvarchar(100)      NULL," & _
    "Status       int                NULL," & _
    "SawPercent   float              NULL," & _
    "ValPerAc     money              NULL," & _
    "ValPerMbf    money              NULL," & _
    "ValPerHcf    money              NULL," & _
    "FormClass    bit                NULL," & _
    "dtExecuted   smalldatetime      NULL," & _
    "dtTerminated smalldatetime      NULL," & _
    "Forester     nvarchar(24)       NULL," & _
    "SaleName     nvarchar(48)       NULL," & _
    "gisLink      nvarchar(10)       NULL," & _
    "cords        int                NULL," & _
    "valcords     money              NULL," & _
    "valothr      money              NULL," & _
    "ObjectID     int IDENTITY(1,1)  NOT NULL," & _
    "CONSTRAINT   [PK_Main] PRIMARY KEY CLUSTERED" & _
    "(" & _
      "Dist   ASC," & _
      "Yr     ASC," & _
      "Num    ASC," & _
      "Type   ASC" & _
    ")" & _
  ");"


             szQuery= _
             "SELECT " & _
               "Dist, " & _
               "Yr, " & _
               "Num, " & _
               "Type, " & _
               "BF, " & _
               "Hcf, " & _
               "Acres, " & _
               "bidPrice, " & _
               "strBuyer, " & _
               "SawPercent, " & _
               "dtExecuted, " & _
               "Status " & _
             "FROM " & _
               "Main " & _
             "WHERE " & _
               "Dist=" & Trim$(Str$(i)) & " AND " & _
               "Type" & strCriteria & " AND " & _
               "dtExecuted>=" & strDtFirst & " And " & _
               "dtExecuted<=" & strDtLast & " " & _
             "ORDER BY " & _
               "Yr, Num;"

        szQuery= _
        "SELECT " & _
          "Species.Species, " & _
          "Species.NetVol, " & _
          "Main.dtExecuted " & _
        "FROM " & _
          "Main " & _
        "LEFT JOIN " & _
          "Species " & _
        "ON " & _
          "(Main.Type = Species.Type) AND " & _
          "(Main.Num = Species.Num) AND " & _
          "(Main.Yr = Species.Yr) AND " & _
          "(Main.Dist = Species.Dist) " & _
        "WHERE " & _
          "(((Species.Species) Is Not Null) AND " & _
          "((Species.NetVol) Is Not Null) AND " & _
          "((Main.dtExecuted)>="+strDtFirst+" And " & _
          "(Main.dtExecuted)<="+strDtLast+"));"

So far I've never hit PowerBASIC's limit. Every time I get doing something like that and keep getting away with it I think nice thoughts of Mr. Zale.

[Mel Bishop]

Have you considered concanitation?

i.e., t$ = a$ + b$ + c$ etc.
***************************

Nevermind. I misread your post.

[Bern Ertl]

I did a bit more testing and it appears the problem is that my function call with the large string literal is located inside a MACRO. If I copy the same code directly into a function, it compiles without error.

[Michael Mattias]

Somewhere in help is a documented number of characters limit for MACROs.

[Cliff Nichols]

Not sure about Literals, but at some point I would think "Under-The-Hood" would become either

String - Directly from the docs ("Dynamic strings can contain up to approximately 2 Gb (2^31) characters")

Asciiz String - Directly from the docs ("STATIC and GLOBAL Scalar (non-array) ASCIIZ strings may be up to 16,777,216 bytes each.")

as a further point of examination that I have not done myself but could be easily tested would be "Are the Characters wide? or not?)....safe bet would be ASSUME 2 bytes per character, but testing point would be 1 byte per char

[Gösta H. Lovgren-2]

Just for fun (I like to see the numbers roll over). The string rolls over after about 5 or 6 hundred million characters, several times, then GPF's.

No point here, just a curiosity.

'

'PBWIN 9.00 - WinApi 05/2008 - XP Pro SP3
#Dim All 
#Compile Exe  
#Include "WIN32API.INC"
'
Global hdlg As Dword                
%Id_Exit_Btn = 1000
%Id_Sample_Textbox = 1001
%Id_Show_Result_Btn = 1002
' 
Macro Common_Locals 'Macro easier than retyping and maintains coding consistency
  Global Dlg_hght, Dlg_Wd As Long 'Global in case want to use in Controls
  Local Row, col, hght, wd, Longest,ctr, ln, ln1, i As Long
  Local  l, s As String
End Macro  
'
CallBack Function Dialog_Processor              
  Common_Locals
  Select Case CbMsg     'This is TO determine the message TYPE 
     '       
     Case %WM_INITDIALOG'<- Initialiaton when the program loads 
     '
     Case %WM_SYSCOMMAND 'Traps Any Alt key but only F4 closes              
     '
     Case %WM_COMMAND  'This processes command messages
       Select Case CbCtl
         Case %Id_Show_Result_Btn 
            For ctr = 1 To 1000000 'million
                s$ = s$ & String$(9999973,  (ctr Mod 128))
                Control Set Text CbHndl, %Id_Sample_Textbox, Using$("#, times String = #, Bytes long   ", ctr, Len(s$)) & Right$(s$, 1000)
                Control ReDraw CB.Hndl, %Id_Sample_Textbox
            Next ctr  

  ? Using$("string = #, characters", Len(s$)),, "Done testing"
              ? l$, , FuncName$
         Case %Id_Exit_Btn
           Select Case CbCtlMsg        
              Case 0
                Dialog End CbHndl 'Applikation beenden
           End Select
       End Select
  End Select
End Function
'
Function PBMain
  Common_Locals
  Dlg_hght = 400
  Dlg_Wd = 400
  Dialog New Pixels, hdlg, "Demo", , , Dlg_Wd, Dlg_Hght, %WS_SYSMENU To hdlg 'centered
  Row = 10
  col = 10
  Wd = 40
  Hght = 12
  Control Add Label, hdlg, -1, " Name & Address ", Col, Row, Wd, Hght
  
  s$ = "Hagstrom, Borje" & $CrLf & _
       "123 PBWin Avenue" & $CrLf & _
       "PowerBasic, FL 12345"
         
  Col = Col + Wd + 10 'just past label 
  Hght = 15 * 10 'Plenty room for 10 lines of text
  Wd = Dlg_Wd - 40 - 30 'minus the label and leave a little
  Control Add TextBox, hdlg, %Id_Sample_Textbox, s$, Col, Row, Wd, Hght, %ES_WantReturn Or %ES_MultiLine
   hght = 25   
   Wd = Dlg_Wd - 20
   Col = 10 'center
   Row = Dlg_hght - (Hght * 2) - 4 'Just off bottom
     Control Add Button, hdlg, %Id_Show_Result_Btn, "Concatenate for a long timw", col, row, Wd, Hght
   Row = Dlg_hght - Hght - 2 'Just off bottom
     Control Add Button, hdlg, %Id_Exit_Btn, "Abandon Ship", col, row, Wd, Hght
  
     Dialog Show Modal hDlg   Call Dialog_Processor
End Function  '

======================================
"The man who does not read good books
has no advantage
over the man who cannot read them."
Mark Twain (1835-1910)
======================================

[Bern Ertl]

Somewhere in help is a documented number of characters limit for MACROs.

Yep, in the description of the MACRO keyword. 4,000 characters. That's the limit I was hitting.

[John Gleason]

Bern, if you have ver. 9/5 the BUILD$ function can make big strings very fast up to ~150K. If you don't have 9/5, the CHR$ function can substitute in place of BUILD$, but only to ~75K string length, and it is many times slower.

Remember too:

A macro definition may contain replacement text up to approximately 4000 characters. Macros may specify up to 240 parameters, which may occupy up to approximately 2000 bytes total expanded space per macro.

Macro Function substitutions are limited to an expanded total of approximately 16000 characters per line of original source code.

#COMPILE EXE
#DIM ALL

FUNCTION PBMAIN () AS LONG
    LOCAL s AS STRING, ii AS LONG

    FOR ii = 1 TO 1000000
       bigString(s)
       myFunction(s)
    NEXT

    ? "Wowie, I just built and checked 2.7 gigs of strings!"

END FUNCTION

FUNCTION myFunction(s AS STRING) AS BYTE
   FUNCTION = ASC(s, 1000)
END FUNCTION

FUNCTION bigString(bStr AS STRING) AS LONG
   bStr = BUILD$("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", _
                 "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb", _
                 "ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc", _
                 "ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd", _
                 "eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee", _
                 "fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", _
                 "ggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg", _
                 "hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh", _
                 "iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiib", _
                 "jjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj", _
                 "kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk", _
                 "lllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll", _
                 "mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm", _
                 "nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn", _
                 "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", _
                 "bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb", _
                 "ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc", _
                 "ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd", _
                 "eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee", _
                 "fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", _
                 "ggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggg", _
                 "hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh", _
                 "iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiib", _
                 "jjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjj", _
                 "kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk", _
                 "lllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll", _
                 "mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm", _
                 "nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn")
END FUNCTION

[Michael Mattias]

The string rolls over after about 5 or 6 hundred million characters, several times, then GPF's.

I'll bet testing the system ERR value would have told you something was wrong. Best guess is error 7, out of memory.