PRB: MOD() with One Negative Number Returns Incorrect Result

• Microsoft FoxPro for Windows, version 2.60a
• Microsoft Visual FoxPro for Windows, version 3.0

SYMPTOMS

When using the MOD() function with one negative number and the expected result is the numerator, FoxPro returns the wrong value. For example, MOD(9,-10) returns -1. The correct result should be 9.

CAUSE

This occurs because the MOD() function was designed to maintain compatibility with the dBASE MOD() function, which also returns this result.

NOTE: dBASE is manufactured by Borland International Inc., a vendor independent of Microsoft; we make no warranty, implied or otherwise, regarding this product's performance or reliability.

RESOLUTION

Create a function similar to the following and use this function instead of MOD().

   FUNCTION INTMOD
   PARAMETER x,y         && where x is the numerator, y is the denominator
   z = x - INT(x/y)*y
   RETURN z              && where z is the expected result

STATUS

This behavior is by design.