Can you provide one or more COBOL coding techniques or recommendations, based on your experience, where efficiencies can be gained?
QUESTION POSED ON: 23 MAR 2005
QUESTION ANSWERED BY: Tom Ross
Yes, the biggest one would be to avoid using subscripts -- use indexes instead. By the way, all of my performance tips are available in my SHARE presentation called LE Performance Tips and Techniques.
COBOL coding tips -- table element references
Given these data descriptions:
77 SUB1 PIC S9(4) USAGE BINARY.
01 GRP1.
05 TAB1 OCCURS 1000 INDEXED BY TABINDX.
10 SALES PIC 9(7) PACKED-DECIMAL.
10 EXPENSES PIC 9(7) PACKED-DECIMAL.
10 INVENTORY PIC 9(7) PACKED-DECIMAL.
Slow code:
PERFORM VARYING SUB1
FROM 1 BY 1
UNTIL SUB1 > 1000
COMPUTE SALES-TOTAL = SALES-TOTAL + SALES(SUB1)
COMPUTE EXPENSE-TOTAL = EXPENSE-TOTAL + EXPENSES(SUB1)
COMPUTE INVENTORY-TOTAL = INVENTORY-TOTAL + INVENTORY(SUB1)
END-PERFORM
Fast code:
PERFORM VARYING TABINDX
FROM 1 BY 1
UNTIL TABINDX > 1000
COMPUTE SALES-TOTAL = SALES-TOTAL + SALES(TABINDX)
COMPUTE EXPENSE-TOTAL = EXPENSE-TOTAL + EXPENSES(TABINDX)
COMPUTE INVENTORY-TOTAL = INVENTORY-TOTAL + INVENTORY(TABINDX)
END-PERFORM
|
