Microsoft KB Archive/39379

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QB.EXE 4.50 "Binding..." then Hang If SWAP User-TYPE Strings

Article ID: 39379

Article Last Modified on 11/21/2006

This article was previously published under Q39379


SWAPping two string variables that are fields of a user-defined type can display the "Binding..." message and then hang the QuickBasic QB.EXE Version 4.50 editor. Hanging does not happen SWAPping non-user-defined type strings or other types of variables. The hanging does not occur in programs compiled with BC.EXE Version 4.50, it is just a QB.EXE editor problem.


Microsoft has confirmed this to be a bug in Version 4.50. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

QB.EXE Versions 4.00 and 4.00b do not have this problem.


Putting the TYPE variables in either $DYNAMIC or $STATIC arrays still hangs. If an INTEGER or DOUBLE appears in the record before the string field that is being swapped, then you can usually warm reboot, otherwise it usually requires a cold reboot. Other variables such as floating point or other TYPES do not prevent the cold reboot. Which String is swapped (1-5) in the following record makes no difference.

Swapping any non-string type of field in a user-defined record does not hang the computer. Swapping both variable- and fixed-length strings as single variables (not in record) also does not hang the computer.

The following code demonstrates the problem:

   TYPE rectype
      num1 AS INTEGER
      string1 AS STRING * 16
      string2 AS STRING * 16
      string3 AS STRING * 16
      string4 AS STRING * 16
      string5 AS STRING * 16
   DIM var1  AS rectype, var2 AS rectype
   var1.string1 = "String1"
   var2.string1 = "String2"
   SWAP var1.string1, var2.string1
   ' The QB.EXE environment will freeze up at this SWAP statement.

To work around the problem, use a standard swapping technique with two variables and a temporary variable:

   DIM var1 as rectype, var2 as rectype, temp as rectype
   temp.string1 = var1.string1      ' 1. a -> temp
   var1.string1 = var2.string1      ' 2. b -> a
   var2.string1 = temp.string1      ' 3. temp -> b

Additional query words: QuickBas buglist4.50

Keywords: KB39379