Compaq COBOL AAQ2G1FTK - Manual (Page 570)

Programming Productivity Tools
C.3 Ladebug Debugger (Tru64 UNIX)
8. Use the list command to display the source lines where you set breakpoints.
(ladebug) list 43,50
43 PERFORM LOOK-BACK VARYING SUB-1 FROM 20 BY -1
44 UNTIL TEMP-CHAR (SUB-1) NOT = SPACE.
45 MOVE SUB-1 TO CHARCT.
46 PERFORM MOVE-IT VARYING SUB-2 FROM 1 BY 1 UNTIL SUB-1 = 0.
47 MOVE HOLD-WORD TO TEMP-WORD.
48 MOVE-IT.
49
MOVE TEMP-CHAR (SUB-1) TO HOLD-CHAR (SUB-2).
50 SUBTRACT 1 FROM SUB-1.
9. Set a tracepoint at line 15 of TESTA.
(ladebug) trace at 15
[#3: trace at "testa.cob":15 ]
10. Set a watchpoint on the data item DISP-COUNT. When an instruction tries
to change the contents of DISP-COUNT, the debugger returns control to you.
(ladebug) stop disp-count of testa-data
[#4: stop if DISP-COUNT of TESTA-DATA changes ]
11. Execution resumes with the cont command. Each time line 50 in TESTB
executes, the debugger executes the command list associated with this line; it
displays the contents of HOLD-CHARS and SUB-1, then resumes execution.
Finally, the debugger returns control to the user when the breakpoint at line
47 is reached.
(ladebug) cont
[3] when [TESTB:50 0x120001c1c]
"c
"
3
[3] when [TESTB:50 0x120001c1c]
"cb
"
2
[3] when [TESTB:50 0x120001c1c]
"cba
"
1
[2] stopped at [TESTB:47 0x120001ba4]
47 MOVE HOLD-WORD TO TEMP-WORD.
12. Examine the contents of SUB-1.
(ladebug) whatis sub-1
unsigned short SUB-1
(ladebug) print sub-1
0
13. Deposit the value –42 into data item SUB-2.
(ladebug) whatis sub-2
pic s99 usage comp-3 SUB-2
(ladebug) assign sub-2=-42
14. Examine the contents of SUB-2.
(ladebug) print sub-2
-42
15. Examine the contents of CHARCT, whose picture is 99V99.
(ladebug) whatis charct
pic 99v99 usage display charct
(ladebug) print charct
3.00
C–6 Programming Productivity Tools