How To Use the Assert Method for Debugging

MORE INFORMATION

The following syntax is used for the Assert method: The Assert method syntax has the following object qualifier and part:

      Part            Description
      ----            -----------
      Debug           Required. The Assert method only applies to the
                      Debug object.

      expression      Required. Any logical expression.
				

The Assert method forces a design-time break at the Assert statement when the expression evaluates to False. If the expression evaluates as True, program operation continues. For example:

      Function myFunction (x as Long,y as Long, z as Long) as Long
          Debug.Assert (x<>0 And y<>0 And z<>0)
          myFunction = 1/x + 1/y + 1/z
      End Function
				

If you call myFunction as:

      q = myFunction (1,2,3)
				

the program continues as normal. However, passing a zero as any one of the parameters forces a break. The following example breaks at the Assert statement:

      q = myFunction (1,0,3)
				

The above example allows testing for inappropriate parameters to protect against a division by zero error. If a break occurs at the Assert statement, you can check the locals window to determine which value is inappropriate. This is especially useful when the argument values come from other functions:

     q = myFunction ( calcX(), calcY(), calcZ() )
				

The Assert method is only used for debugging. During compiling, Microsoft Visual Basic always removes Assert statements from the final code. There is no workaround for this behavior.