AutoLISP Developer's Guide > Using the Visual LISP Environment > Debugging Programs > Learning by Example > Stepping through the Debugging Example > 
Stepping through the Program
 
 
 

The Step commands allow you to move through a program by executing one or more expressions at a time.

To step through a program from a breakpoint

  1. Click the Step Into button, or choose Debug Step Into from the VLISP menu. You can also press F8 to issue the Step Into command.

    Execution begins and halts before evaluation of the inner parenthetical expression, that is, before the specified division occurs. The expression is highlighted, as shown in the following figure:

    Now look at the Step Indicator button on the Debug toolbar; it is the last button on that toolbar.

    The Step Indicator button is active when you are stepping through a program. It indicates where you are in relation to the expression at the breakpoint. The current symbol indicates that you are stopped just before an open parenthesis.

  2. Click the Step Into button again. The cursor moves to a position directly after the evaluated expression, and the Step Indicator button indicates this.
  3. Click the Step Into button again. The cursor moves to the end of the entire statement (the expression and all nested expressions).
  4. Click the Step Into button again and the cursor moves to a position just before the beginning of the statement on the next line:

  5. Now take a bigger step. Click the Step Over button, or choose Debug Step Over from the menu, or press SHIFT + F8 to issue this command:

With the Step Over command, VLISP evaluates an entire expression (and all nested expressions), then stops at the end of the overall expression. The cursor moves to the end of the evaluated expression.