FIX: Comparision with Zero Generates Bad Code

ID: Q156913

The information in this article applies to:

Microsoft Visual J++ 1.0

SYMPTOMS

The following code sets the Boolean to true, whereas the correct value is false:

   int i = 0;
   boolean b = (0 < i);

b is set to true.

CAUSE

This problem is due to bad code generated by the compiler.

WORKAROUND

Change the above code as shown below:

   int i = 0;
   boolean b = (i > 0);

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. This problem has been fixed in Visual J++ 1.1.

MORE INFORMATION

The problem occurs only when 0 is the literal on the left side of the operator. If the left side of the operator is a variable or a literal other than 0, then the expression is evaluated correctly. The following expressions are evaluated correctly:

   int i = 0;
   int j = 0;

   boolean b = (i < j);

   i++;

   b = (1 < i);

Some of the common places where you might run into this bug are in conditional statements or loops.

Steps to Reproduce Problem

Use the following code to reproduce the problem:

   int i = 0;
   boolean b = (0 < i);

Additional query words: comparison

REFERENCES

For the latest Knowledge Base articles and other support information on Visual J++ and the SDK for Java, see the following page on the Microsoft Technical Support site:

   http://support.microsoft.com/support/visualj/ 
   http://support.microsoft.com/support/java/

Keywords          : kbCommandLine 
Version           : 1.0
Platform          : WINDOWS
Issue type        : kbbug
Solution Type     : kbfix

Last Reviewed: January 24, 1998