Eval Function

 

Evaluates an expression and returns the result.

Eval(expression)

expression

Required. String containing any legal VBScript expression.

In VBScript, x = y can be interpreted two ways. The first is as an assignment statement, where the value of y is assigned to x. The second interpretation is as an expression that tests if x and y have the same value. If they do, the result is True; if they are not, the result is False. The Eval method always uses the second interpretation, whereas the Execute statement always uses the first.

System_CAPS_noteNote

In Microsoft JScript, no confusion exists between assignment and comparison, because the assignment operator (=) is different from the comparison operator (==).

The following example illustrates the use of the Eval function:

Sub GuessANumber
   Dim Guess, RndNum
   RndNum = Int((100) * Rnd(1) + 1)
   Guess = CInt(InputBox("Enter your guess:",,0))
   Do
      If Eval("Guess = RndNum") Then
         MsgBox "Congratulations! You guessed it!"
         Exit Sub
      Else
         Guess = CInt(InputBox("Sorry! Try again.",,0))
      End If
   Loop Until Guess = 0
End Sub

Requirements

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