PRB: Correct Usage of "&" and "AND" in Visual Basic 4.0

 Last reviewed: March 27, 1997
Article ID: Q165920
The information in this article applies to:
  • Microsoft Visual Basic Standard, Professional, and Enterprise Editions, 16-bit and 32-bit, for Windows, version 4.0

SYMPTOMS

This code works in Visual Basic 3.0: 

     If Form1.Text1.Text = "" & Form1.Text2.Text = "" Then...
but fails in Visual Basic 4,0 with a "type mismatch" error.

The correct syntax for this statement is: 

     If Form1.Text1.Text = "" And Form1.Text2.Text = "" Then...
Form1.Text1.Text="" will evaluate to either a TRUE or FALSE in Visual Basic 4.0. In Visual Basic 3.0, the same statement would evaluate to either a 1 or a 0.

Confusing the concatenation operator "&" with the logical operator "AND" will result in "type mismatch errors."

CAUSE

This is a result of the data type of (Boolean) being added to Visual Basic 4.0.

RESOLUTION

When performing logical comparisons between operands, be sure to use the logical operators (AND, OR) as opposed to the concatenation operator "&" in Visual Basic 4.0.

STATUS

This is by design.

MORE INFORMATION

In Visual Basic 3.0, a logical comparison between operands would result in either a 1 or a 0 being returned. With Visual Basic 4.0, a logical data type has been added so that a logical comparison between two operands will result in either a "TRUE" or "FALSE" value being returned. Attempting to use the concatenation operator "&" can not be performed in Visual Basic 4.0 on these logical data types. Therefore, an error is raised.

Keywords : PrgOther vb4all vb4win kbbug
Version : 4.0
Platform : WINDOWS
Issue type : kbbug

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Last reviewed: March 27, 1997
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