

modulus                     Definition                    modulus




Modulus is the operation that returns the remainder of a division
operation.   For example,  12 modulus  four equals  zero, because
when  12 is  divided by  four it leaves  no remainder.   The term
``modulo'' also refers to  the product of a modulus operation; in
the above example, the modulo  is zero.  In C, the modulus opera-
tion is indicated with  a percent sign `%'; therefore, 12 modulus
4 is written 1122%44.

The modulus  operation often is used to trim  numbers to a preset
range.  For  example, if you  wanted to create a  list of single-
digit random numbers, you would use the command:


        rand()%10


This is demonstrated by the following example.

***** Example *****

This  example prints  a list of  20 single-digit  random numbers.
The random-number  table is seeded with a  portion of the current
system time.


main()
{
        long nowhere;   /* place to put unused data */
        int counter;



        srand((int)time(&nowhere));
        for (counter = 0; counter <20; counter++)
                printf("%d\n", rand()%10);
}


***** See Also *****

definitions, operator

***** Notes *****

The implementation  of C defines  how a modulus  operator behaves
when  it operates  upon  numbers with  different  signs.  On  the
i8086,


        10 % -4


yields -2.  This is not mathematical modulus, which is +2.



COHERENT Lexicon                                           Page 1


