GNU Info

(python2.1-ref.info)Shifting operations

---

Next: Binary bit-wise operations Prev: Binary arithmetic operations Up: Expressions

---

Enter node , (file) or (file)node

Shifting operations
===================

The shifting operations have lower priority than the arithmetic
operations:

     shift_expr:     a_expr | shift_expr ( "<<" | ">>" ) a_expr

These operators accept plain or long integers as arguments.  The
arguments are converted to a common type.  They shift the first
argument to the left or right by the number of bits given by the second
argument.

A right shift by N bits is defined as division by `pow(2,N)'.  A left
shift by N bits is defined as multiplication with `pow(2,N)'; for plain
integers there is no overflow check so in that case the operation drops
bits and flips the sign if the result is not less than `pow(2,31)' in
absolute value.  Negative shift counts raise a `ValueError' exception.