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8.167 LEADZ — Number of leading zero bits of an integer ¶

Description:

LEADZ returns the number of leading zero bits of an integer.

Standard:

Fortran 2008 and later

Class:

Elemental function

Syntax:

RESULT = LEADZ(I)

Arguments:

I	Shall be of type INTEGER.

Return value:

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).

Example:

PROGRAM test_leadz
  WRITE (*,*) BIT_SIZE(1)  ! prints 32
  WRITE (*,*) LEADZ(1)     ! prints 31
END PROGRAM

See also:

BIT_SIZE — Bit size inquiry function,
TRAILZ — Number of trailing zero bits of an integer,
POPCNT — Number of bits set,
POPPAR — Parity of the number of bits set