PRB: For Loop w/ Integer Counter & Increment <=.5 Causes Hang

- Standard and Professional Editions of Microsoft Visual Basic for

  Windows, versions 2.0 and 3.0

  versions 7.0 and 7.1

SYMPTOMS

If you write a FOR loop with an INTEGER or LONG variable as the FOR loop counter and use a floating point value less than or equal to 0.5 as the FOR loop increment, the loop never terminates. This causes the computer to hang (stop responding to input).

CAUSE

All Basic programs convert floating point values less than 0.5 to the integer value 0.

RESOLUTION

To stop a program that is executing in this type of an endless loop, press CTRL+BREAK.

STATUS

This behavior is by design. In other words, this is not a problem with the FOR statement; this is the way Basic is designed to operate.

MORE INFORMATION

Steps to Reproduce Behavior in Visual Basic for Windows

1. 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.

2. Add the following code to the Form_Click event procedure for Form1:

      Sub Form_Click ()
         For j& = .005 To .0062 Step .0001
            total! = total! + j&
         Next j&
         Print total!
      End Sub
   
   

3. Press F5 to run the example.

To change this example program so that the loop terminates, change the type of the counter variable from LONG to SINGLE (change j& to j!).