Intel(R) Fortran Compiler for Linux* Systems User's Guide Volume I ...

Intel® Fortran Compiler for Linux* Systems User's Guide, Volume I: Building
Applications
7. The command print n, k displays the current values of variables N
and K. Their values are correct at this point in the execution of the
program.
8. The two step commands continue executing the program into the loop
(lines 9 to 11) that copies and squares all nonzero elements of INARR into
OUTARR. Certain commands can be abbreviated. In this example, the s
command is an abbreviation of the step command.
9. The command print i, k displays the current values of variables I and
K. Variable I has the expected value, 1. But variable K has the value 0
instead of the expected value, 1. To fix this error, K should be incremented
in the loop just before it is used in line 11.
10. The assign command assigns K the value 1.
11. The watch variable k command sets a watchpoint that is triggered
every time the value of variable K changes. In the original version of the
program, this watchpoint is never triggered, indicating that the value of
variable K never changes (a programming error).
12. To test the patch, the cont command (an abbreviation of continue)
resumes execution from the current location. The program output shows
that the patched program works properly, but only for the first array
element. Because the watchpoint (watch variable k command) does
not occur, the value of K did not change and there is a problem. The idb
message "Process has exited with status 0" shows that the program
executed to completion.
13. The quit command returns control to the shell so that you can correct the
source file and recompile and relink the program.
14. The shell command vi runs a text editor and the source file is edited to
add K = K + 1 after line 10, as shown. (Compiler-assigned line numbers
have been added to clarify the example.)
15. The revised program is compiled and linked. The shell command idb
squares starts the debugger, using the revised program so that its
correct execution can be verified.
16. The when at 12 {print k} command reports the value of K at each
iteration through the loop.
17. The run command starts execution.
18. The displayed values of K confirm that the program is running correctly.
19. The quit command ends the debugging session, returning control to the
shell.
Displaying Variables in the Debugger
To refer to a variable, use either the uppercase or lowercase letters. For
example:
(idb) print J
97