Re: Static vs dynamic evaluation anomaly?

["Jeffrey R. Carter" <jrcarter@acm.org>]

Matt Jaffe wrote:
>   A student of mine stumbled over a problem that I can reproduce but 
> can't explain.  It manifests itself in the two different values computed 
> by two almost identical expressions when an integer variable is replaced 
> by an integer literal of the same value.  Here's a sample output:
> 
>     The test pattern, X, is a modulo 2**6 integer = 31 or 2#11111#
> 
>     When J=0, X*2**J = 31 or 2#11111#        but X*2**0 = 31 or 2#11111#
>     When J=1, X*2**J = 62 or 2#111110#       but X*2**1 = 62 or 2#111110#
>     When J=2, X*2**J =124 or 2#1111100#      but X*2**2 = 60 or 2#111100#
>     When J=3, X*2**J =248 or 2#11111000#     but X*2**3 = 56 or 2#111000#
>     When J=4, X*2**J =240 or 2#11110000#     but X*2**4 = 48 or 2#110000#
>     When J=5, X*2**J =224 or 2#11100000#     but X*2**5 = 32 or 2#100000#
> 
> Here are the relevant declarations:
> 
>   type Six_Bits is mod 2**6;
>    package Six_Bit_IO is new Ada.Text_IO.Modular_IO(Six_Bits); use 
> Six_Bit_IO;
>    X : Six_Bits := 31;

I would need to see more to comment, but I suggest you eliminate all use 
clauses and see if that makes a difference.

-- 
Jeff Carter
"Pray that there's intelligent life somewhere up in
space, 'cause there's bugger all down here on earth."
Monty Python's Meaning of Life
61