Debugging with a Debugging File

Why you debug using a debugging file

If your program contains an error in logic, then the program might execute without producing an error message, but it will execute the wrong set of commands or produce incorrect results. For example, suppose you write a Boolean expression incorrectly in an IF command (for example, you use NE instead of EQ). The program will execute the commands you specified, but it will do so under the wrong conditions.

To find an error in program logic, you often need to see the order in which the commands are being executed. One way you can do this is to create a debugging file and then examine the file to diagnose any problems in your programs.

Creating a debugging file

Command you use to create a debugging file

To create a debugging file, you use the DBGOUTFILE command. The simplified syntax of the DBGOUTFILE command is shown below.

DBGOUTFILE {EOF|[APPEND] file-id [NOCACHE]}

The EOF keyword specifies that the current debugging file should be closed, and that debugging output should no longer be sent to a file.

The APPEND keyword specifies that the output should be added to the end of an existing disk file. If you omit this argument and a file exists with the specified name, then the new output replaces the current contents of the file.

The argument file-id specifies the name of the file to receive the debugging output.

The NOCACHE keyword causes the OLAP DML to write to the debugging file each time it executes a line of code. Without this keyword, file I/O activity is reduced by saving text and writing it periodically to the file.

For the complete syntax of the DBGOUTFILE command, see the entry for the command in OLAP DML Reference, which you can access by selecting Language from the Help menu in OLAP Worksheet.

Specifying the contents of the debugging file

Using the DBGOUTFILE command merely creates a file for debugging. To specify that you want each program line to be sent, as it executes, to the debugging file, set the PRGTRACE option to YES.

As outlined below, using either the ECHOPROMPT or IFCOPY option, you can also specify that additional information should be included in the debugging file.

IF you want the debugging file to interweave the program lines with . . .	THEN set the . . .
both the program's input and error messages,	ECHOPROMPT option to YES.
only the program's input,	IFCOPY option to YES.

For the syntax of the ECHOPROMPT, IFCOPY, and PRGTRACE options, see the entry for each option in OLAP DML Reference.

Example: Debugging using a debugging file

Creating a debugging file

The following commands create a useful debugging file called debug.txt in the current working directory.

prgtrace = yes
echoprompt = yes
dbgoutfile 'debug.txt'

After executing these commands, you can run your program as usual. To close the debugging file, execute this command.

dbgoutfile eof

Sample Program Code

In the following sample program, the first LIMIT command has a syntax error.

DEFINE ERROR_TRAP PROGRAM
PROGRAM
trap on traplabel
limit month to first badarg
limit product to first 3
limit district to first 3
report sales
traplabel:
signal errorname errortext
END

Debugging File Output

With PRGTRACE and ECHOPROMPT both set to YES and with DBGOUTFILE set to send debugging output to a file called debug.txt, the following text should be sent to the debug.txt file when you execute the ERROR_TRAP program.

(PRG= ERROR_TRAP) 
(PRG= ERROR_TRAP) trap on traplabel
(PRG= ERROR_TRAP) 
(PRG: ERROR_TRAP) limit month to first badarg
ERROR: BADARG does not exist in any attached database.
(PRG= ERROR_TRAP) traplabel:
(PRG= ERROR_TRAP) signal errorname errortext
ERROR: BADARG does not exist in any attached database.

Related information

For more information, see the following table.

IF you want documentation about . . .	THEN see . . .
specifying the file to use for output,	"Directing Output"
individual OLAP DML commands,	the entry for the command in OLAP DML Reference