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IsMissing Function
This standard VB function is used to determine whether an optional argument for a procedure has been supplied by the caller. Syntax
IsMissing(argname)
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An optional argument for a subprogram, function, Siebel VB statement, or Siebel VB function |
Returns
-1 (TRUE) if an optional argument was not supplied by the user; 0 (FALSE) otherwise. Usage
IsMissing is used in procedures that have optional arguments to find out whether the argument's value was supplied or not. Example
This example prints a list of uppercase characters. The quantity printed is determined by the user. If the user wants to print every character, the Function myfunc is called without any argument. The function uses IsMissing to determine whether to print every uppercase character or just the quantity specified by the user. Function myfunc(Optional arg1) If IsMissing(arg1) = -1 then arg1 = 26 End If msgtext = "The letters are: " & Chr$(10) For x = 1 to arg1 msgtext = msgtext & Chr$(x + 64) & Chr$(10) Next x End Function
Sub Button_Click Dim arg1 arg1 = 0 If arg1 = 0 then myfunc() Else myfunc(arg1) End If End Sub
Related Topics
Function...End Function Statement
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