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Tip of the Day
Language: Visual Basic
Expertise: Beginner
Jan 28, 1999



Building the Right Environment to Support AI, Machine Learning and Deep Learning

Watch Out for "()" When Calling Subroutines

To call a subroutine, you can use the Call statement or simply the name of the subroutine:
	Call MyRoutine(firstParameter)
	MyRoutine firstParameter
Notice you don't include the parentheses in the second case. If you do, VB assumes you mean them as an operator. VB then determines the value of the parameter and passes the value to the routine, instead of passing the reference as expected. This is apparent in this example:
	Call MyRoutine(Text1)
This passes the text-box control to MyRoutine. If you did it without the Call statement, VB evaluates Text1, which returns the default property value of the text box:
This default property is the text-box text. So, if the routine expects a control, you pass the text string from the control instead and will receive a type-mismatch error. To prevent this, always use the Call statement or don't put parentheses in when calling a subroutine.
Deborah Kurata
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