PRB: SendKeys May Return Illegal Function Call Error (87773)

SYMPTOMS

The SendKeys statement reports the error "Illegal function call" when its argument contains an incorrectly formatted string. This article describes specific circumstances that cause this error, and contains a code example that shows how to send any string with SendKeys.

CAUSE

The following characters have special meaning to the SendKeys statement:

      + ^ % ~ ( ) [ ] { }

The SendKeys statement reports an "Illegal function call" error if its argument contains one of the following, not enclosed in braces:

An unmatched parenthesis () or bracket {}
A bracket []
Braces containing an undefined character sequence, such as {abc}

RESOLUTION

To prevent the SendKeys statement from interpreting a character, enclose the character in braces {}. For example, to send the string

The interest rate is 5% (annually).

Use the following SendKeys syntax:

      SendKeys "The interest rate is 5{%} {(}annually{)}."

MORE INFORMATION

Step-by-Step Example

The following example demonstrates how to use the SendKeys statement to send strings that would normally cause an "Illegal function call" error:

Start Visual Basic or from the File menu, choose New Project (ALT, F, N) if Visual Basic is already running. Form1 is created by default.
Place a text box (Text1) on Form1.
Place a command button (Command1) on Form1.

Enter the following code:

   Sub Command1_Click ()
      Text1.SetFocus
      SendKeys sendkeys_prepare("1+2^5% ")
      SendKeys sendkeys_prepare("[] ")
      SendKeys sendkeys_prepare("{abc}")
   End Sub

   ' The following function puts braces {} around characters that
   ' are special to the SendKeys statement.
   Function sendkeys_prepare (in As String) As String
      For i% = 1 To Len(in)
         ' Get the next character into c$.
         c$ = Mid$(in, i%, 1)
         ' If c$ is one of the special characters.
         If InStr("+^%~()[]{}", c$) Then
            out$ = out$ + "{" + c$ + "}"
         Else
            out$ = out$ + c$
         End If
      Next
      sendkeys_prepare = out$
   End Function

Press F5 to run the program. Click Command1. Some example text containing characters special to SendKeys appear in Text1.