TRAILZ — Number of trailing zero bits of an integer ¶TRAILZ returns the number of trailing zero bits of an integer.
Fortran 2008 and later
Elemental function
RESULT = TRAILZ(I)
| I | Shall be of type INTEGER. | 
The type of the return value is the default INTEGER.
If all the bits of I are zero, the result value is BIT_SIZE(I).
PROGRAM test_trailz WRITE (*,*) TRAILZ(8) ! prints 3 END PROGRAM
BIT_SIZE — Bit size inquiry function, 
LEADZ — Number of leading zero bits of an integer, 
POPPAR — Parity of the number of bits set, 
POPCNT — Number of bits set