Branching to Other Sections of Code with GoTo and Call (109780)

MORE INFORMATION

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GoTo

The GoTo statement jumps to and executes the instructions at the specific line label and continues executing until the end of the program is reached.

Call

The Call statement runs a procedure and then returns to the line immediately after the Call statement in the originating procedure. The Call statement can also pass arguments of any declared data type to the called procedure and can transfer control to a Sub procedure, Function procedure, dynamic link library (DLL) procedure, or Macintosh code resource procedure.

The following examples demonstrate how to use GoTo and Call.

Example 1: The Difference Between Call and GoTo

The following Visual Basic procedure demonstrates the difference between using the GoTo statement and the Call statement.

  Sub One()
       MsgBox ("One()")       ' Displays message box.

       ' Sends control to Line10 below.
       ' The GoTo Line10 statement directs the program to branch to the
       ' line labeled "Line10:", the message box "unexecuted code" is
       ' skipped.
       GoTo Line10

       ' This message box is not displayed.
       MsgBox ("unexecuted code")
				

Line10:

       ' Displays message box.
       MsgBox ("Line10 of One()")

       ' The "Call Two()" line executes the subroutine defined as "Two()",
       ' sends a message box indicating that the subprocedure is executing,
       ' then returns to Sub One executing the line immediately after the


       ' Call statement.
       ' Call made to Sub procedure named two()
       Call Two

       ' Message box displayed.
       MsgBox ("back to One(); returning from Two()")

   End Sub

   Sub Two()
       ' Message box displayed.
       MsgBox ("Two()")
   End Sub
				

NOTE: The sample code above does not pass any arguments.

Example 2: An Alternative to the Call Statement

The following Visual Basic code makes a call to a another Sub procedure without using the Call statement.

   Sub One()
       MsgBox ("One()")              ' Message box displayed.
       two                           ' Call made to Sub named two().
       MsgBox ("return from Two()")  ' Message box displayed.
   End Sub

   Sub Two()
       MsgBox ("Two()")              ' Message box displayed.
   End Sub
				

Example 3: Using GoTo for Conditional Branching

The following code shows how you can combine the If...Then...Else statement with the GoTo statement to provide more branching options or to create the ability to return to a specific location after the GoTo statement is executed.

  Sub GetInput()

       Dim number as Integer ' Used for input variable.

       ' User input requested. Val() to turn input text into a number.
       number = Val(InputBox("Enter a 1 or a 2."))

       ' Condition that is evaluated based on user input.
       If number = 1 Or number = 2 Then
           GoTo Line1
       Else
           GoTo Line2
       End If
				

Line1:

       MsgBox ("Great! You entered a " & number & ".")
       GoTo LastLine
				

Line2:

       MsgBox ("Sorry, you must enter a 1 or a 2.")
				

LastLine:

       MsgBox ("End of program.")
   End Sub