Can't seem to subract two numbers in a PLSQL function

The following function is intended to divide up a delimited CLOB into a string array:

FUNCTION SPLIT_CLOB(sText IN clob, sDel IN VARCHAR2 := ',') RETURN CLOB_ARRAY IS
         nStartIdx PLS_INTEGER :=开发者_运维百科 1;
         nEndIdx PLS_INTEGER := 1;
         oRet CLOB_ARRAY := CLOB_ARRAY();
     BEGIN
         IF sText IS NULL THEN RETURN oRet; END IF;
         IF DBMS_LOB.getlength(sText) = 0 THEN RETURN oRet; END IF;

         LOOP

            nEndIdx := DBMS_LOB.INSTR(sText, sDel, nStartIdx);

            IF nEndIdx > 0 THEN
               oRet.Extend;
               /* compiler error on this statement: */
               oRet(oRet.LAST) := DBMS_LOB.SUBSTR(sText, (nEndIdx – nStartIdx), nStartIdx);
               nStartIdx := nEndIdx + LENGTH(sDel);
            ELSE
               oRet.Extend();
               oRet(oRet.LAST) := DBMS_LOB.SUBSTR(lob_loc => sText, offset => nStartIdx);
               EXIT;
            END IF;
         END LOOP;

         RETURN oRet;

     END SPLIT_CLOB;

The line:

oRet(oRet.LAST) := DBMS_LOB.SUBSTR(sText, (nEndIdx – nStartIdx), nStartIdx);

throws PLS-00103 compiler errors. But if I change the call to:

oRet(oRet.LAST) := DBMS_LOB.SUBSTR(sText, 5, nStartIdx);

everything is fine. I've tried creating another variable to do the subtraction ahead of time, but ran into the same PLS-00103 error.

Have I lose my touch? Did I forget how to subtract two numbers or something?

Please help. Thanks.

EDIT

Okay, the WEIRDEST thing just happened... in the rest of this package, I know I was subtracting some PLS_INTEGERs somewhere else in a different function.... so I found such an example, then COPY & PASTE the minus sign found in my other function, and the thing compiles...

Thanks for your help...

Why not do the calculation before the

oRet(oRet.LAST) := DBMS_LOB.SUBSTR(sText, (nEndIdx – nStartIdx), nStartIdx); 

eg

calcValue := nEndIdx – nStartIdx;

oRet(oRet.LAST) := DBMS_LOB.SUBSTR(sText, calcValue, nStartIdx); 

"Operations involving patterns as parameters, such as COMPARE, INSTR, and SUBSTR do not support regular expressions or special matching characters (such as % in the LIKE operator in SQL) in the pattern parameter or substrings." http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14258/d_lob.htm

I think you should calculate "nEndIdx – nStartIdx" outside the SUBSTR Function

Substr Ref. http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14258/d_lob.htm#i999349