Knowledge Base

FIX: Comparision with Zero Generates Bad Code

Article ID: 156913

Article Last Modified on 5/12/2007

Microsoft Visual J++ 1.0 Standard Edition

This article was previously published under Q156913

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);

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://www.microsoft.com/mscorp/java/

Additional query words: comparison

Keywords: kbbug kbcommandline kbfix kbvj110fix KB156913