After you write a function or program, you can use several techniques to find and correct errors. You can also build an error-handling command into the function or program itself.
If your function or program allows the user to select from several options, be sure to run it and test each option.
Run-time error messages can locate syntax errors but not errors in program logic. The following techniques may be useful.
| • | Temporarily insert Disp commands to display the values of critical variables. |
| • | To confirm that a loop is executed the correct number of times, use Disp to display the counter variable or the values in the conditional test. |
| • | To confirm that a subroutine is executed, use Disp to display messages such as “Entering subroutine” and “Exiting subroutine” at the beginning and end of the subroutine. |
| • | To stop a program or function manually, |
| - | Windows®: Hold down the F12 key and press Enter repeatedly. |
| - | Mac®: Hold down the F5 key and press Enter repeatedly. |
| - | Handheld: Hold down the c key and press · repeatedly. |
|
Command |
Description |
|
Try...EndTry |
Defines a block that lets a function or program execute a command and, if necessary, recover from an error generated by that command. |
|
|
Clears the error status and sets system variable |
|
PassErr |
Passes an error to the next level of the Try...EndTry block. |