Texas Instruments TI89TITANIUM User Manual - Page 636

Debugging Techniques Run-time error messages can locate syntax errors but not errors in program logic. The following techniques may be useful. • During testing, do not use local variables so that you can check the variable values after the program stops. When the program is debugged, declare the applicable variables as local. • Within a program, temporarily insert Disp and Pause commands to display the values of critical variables. - Disp and Pause cannot be used in a user-defined function. To temporarily change the function into a program, change Func and EndFunc to Prgm and EndPrgm. Use Disp and Pause to debug the program. Then remove Disp and Pause and change the program back into a function. • To confirm that a loop is executed the correct number of times, display the counter variable or the values in the conditional test. • To confirm that a subroutine is executed, display messages such as Entering subroutine and Exiting subroutine at the beginning and end of the subroutine. Error-Handling Commands Command Try...EndTry ClrErr PassErr Description Defines a program block that lets the program execute a command and, if necessary, recover from an error generated by that command. Clears the error status and sets the error number in system variable Errornum to zero. Passes an error to the next level of the Try...EndTry block. Programming 636