Q65107: Modulus Yields Incorrect Result When Used with /Ot

Article: Q65107
Product(s): See article
Version(s): 2.00 2.01
Operating System(s): MS-DOS
Keyword(s): ENDUSER | buglist2.00 buglist2.01 fixlist2.50 fixlist2.51 | mspl13_c
Last Modified: 31-AUG-1990

The following code using the modulus operator "%" yields incorrect
results under Microsoft QuickC version 2.00 when optimizations are set
to ON or FULL and release mode is selected.

The error also occurs when compiling using the qcl command if you use
the /O, /Ot, or /Ox optimizations.

To avoid the error, upgrade to QuickC version 2.50 or QuickC with
QuickAssembler version 2.51, or avoid the problem optimizations.
Neither version 5.10 or version 6.00 of the Microsoft C Compiler
demonstrate this error.

Sample Code
-----------

#include <stdio.h>

main ()
{
 int x=26,
     Number = 151-(3 * x),
     Onesdigit = Number % 10;

 printf("The one's digit is: %i\n",Onesdigit); // correct output is 3,
                                               // buggy output is 0
}

Microsoft has confirmed this to be a problem with QuickC versions 2.00
and 2.01. This problem is corrected in versions 2.50 and 2.51.

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