Question { 986 }

What is the difference between subscript and index?

Answer

Subscripts are programmer-defined variables, of numeric type--used to reference an array.
Example:
77 WS-SUB PIC 9(04) COMP.
01 WS-TABLE.
05 WS-TABLE-ENTRY OCCURS 5 Times PIC X(80).

In PROCEDURE DIVISION:
MOVE WS-TABLE-ENTRY(WS-SUB) TO...

Indexes are defined by the programmer, but the PICTURE clause is omitted.
Example:
01 WS-TABLE.
05 WS-TABLE-ENTRY OCCURS 5 TIMES INDEXED BY WS-IDX.
10 FILLER PIC X(80).

In PROCEDURE DIVISION:
MOVE WS-TABLE-ENTRY(WS-IDX) TO...

Question { 895 }

What do you understand by passing by reference and passing by content?

Answer

Passing by reference, is passing the ADDRESS of a variable--to a subprogram. The subprogram is able to change the value contained in the variable.

Passing by content is passing the DATA contained within a variable--to a subprogram. The subprogram can NOT change the value of the data in the (calling program's) variable.