Debugging a Basic Program /text/sbasic/shared/01030300.xhp
debugging Basic programs variables; observing values watching variables run-time errors in Basic error codes in Basic breakpoints Call Stack window

Debugging a Basic Program

Breakpoints and Single Step Execution

You can check each line in your Basic program for errors using single step execution. Errors are easily traced since you can immediately see the result of each step. A pointer in the breakpoint column of the Editor indicates the current line. You can also set a breakpoint if you want to force the program to be interrupted at a specific position. Double-click in the breakpoint column at the left of the Editor window to toggle a breakpoint at the corresponding line. When the program reaches a breakpoint, the program execution is interrupted. The single step execution using the Single Step icon causes the program to branch into procedures and functions. The procedure step execution using the Procedure Step icon causes the program to skip over procedures and functions as a single step.

Properties of a Breakpoint

The properties of a breakpoint are available through its context menu by right-clicking the breakpoint in the breakpoint column. You can activate and deactivate a breakpoint by selecting Active from its context menu. When a breakpoint is deactivated, it does not interrupt the program execution. Select Properties from the context menu of a breakpoint or select Breakpoints from the context menu of the breakpoint column to call the Breakpoints dialog where you can specify other breakpoint options. The list displays all breakpoints with the corresponding line number in the source code. You can activate or deactivate a selected breakpoint by checking or clearing the Active box. The Pass Count specifies the number of times the breakpoint can be passed over before the program is interrupted. If you enter 0 (default setting) the program is always interrupted as soon as a breakpoint is encountered. Click Delete to remove the breakpoint from the program.

Observing the Value of Variables

You can monitor the values of a variable by adding it to the Watch window. To add a variable to the list of watched variables, type the variable name in the Watch text box and press Enter. The values of variables are only displayed if they are in scope. Variables that are not defined at the current source code location display ("Out of Scope") instead of a value. You can also include arrays in the Watch window. If you enter the name of an array variable without an index value in the Watch text box, the content of the entire array is displayed. If you rest the mouse over a predefined variable in the Editor at run-time, the content of the variable is displayed in a pop-up box.

The Call Stack Window

Provides an overview of the call hierarchy of procedures and functions. You can determine which procedures and functions called which other procedures and functions at the current point in the source code.

List of Run-Time Errors