Re: confused about == vs === in this equality

*To*: mathgroup at smc.vnet.net*Subject*: [mg103800] Re: confused about == vs === in this equality*From*: pfalloon <pfalloon at gmail.com>*Date*: Tue, 6 Oct 2009 08:02:50 -0400 (EDT)*References*: <20091003104738.LCJ3I.416659.imail@eastrmwml34>

On Oct 6, 5:06 am, Daniel Lichtblau <d... at wolfram.com> wrote: > d... at wolfram.com wrote: > >> ?=== > >> lhs===rhs yields True if the expression lhs is identical to rhs,= and > >> yields > >> False otherwise. > > >> ?== > >> lhs==rhs returns True if lhs and rhs are identical. > > >> But looking at this example: > > >> a = ComplexInfinity; > >> If[a == ComplexInfinity, Print["YES"]] > > >> Expecting it would print "YES", but it does not. it just returns the w= hole > >> thing unevaluated? But > > >> If[a === ComplexInfinity, Print["YES"]] > > >> does return YES. > > >> I guess I am a little confused about the "expression" bit in the > >> definition. > > >> So, when using the 3"=", it is looking at the _value_ of the express= ion, > >> but > >> when using the 2"=", it is looking at the expression _as it is_, i.e=