It should be noted that perl is one of the few languages that computes mod of negative numbers properly. This means that the above algorithm will work fine in Perl for all integers but will work (for example) in C only for non-negative integers. Also the basic mod algorithm needs further enhancement to handle real numbers properly (needing to be able to reply "neither odd nor even"). It would be very interesting to hear how this algorithm performs in other languages (Python, Java, TCL, etc..).
Language Code Output
perl 
for($c=-3;$c<4;$c++){
  printf("%d %d\n",$c,$c % 2); 
}

[download]
 
-3 1
-2 0
-1 1
 0 0
 1 1
 2 0
 3 1
C/C++ 
int c;
for(c=-3;c<4;c++){
  printf("%d  %d\n",c,c%2);
}

[download]
 
-3  -1
-2   0
-1  -1
 0   0
 1   1
 2   0
 3   1

In reply to Re: Checking for odd/even number by lhoward
in thread Checking for odd/even number by Anonymous Monk

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