ffs(3c) — DG/UX 4.30



     ffs(3c)                    DG/UX 4.30                     ffs(3c)



     NAME
          ffs - Return the position of the first set bit in an
          integer.

     SYNOPSIS
          int ffs(), bitnum, number;
          bitnum = ffs(number);



          where   number is the integer tested for the set bit.


     DESCRIPTION
          The ffs function returns the position of the first bit set
          to 1 in an integer; this function comes from the University
          of California Berkeley UNIX (BSD) system.

     RETURNS
          The ffs function returns the first set bit, starting with
          the least significant bit.  For example, ffs(0) returns 0,
          ffs(1) returns 1, and ffs(16) returns 5.

     SEE ALSO
          See also the bcopy, bcmp, and bzero functions.

     EXAMPLE
          The following program demonstrates the ffs function for each
          power of two from 0 - 15 and 0.

          /* Program test for the ffs() function */

          #include <stdio.h>


          int ffs(), i = 1;

          main() {
              printf("ffs(%#08x) = %d.\n", i, ffs(i));
              do {
                  i <<= 1;
                  printf("ffs(%#08x) = %d.\n", i, ffs(i));
              } while (i != 0);
              return 0;
          }










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