Beefy Boxes and Bandwidth Generously Provided by pair Networks
Welcome to the Monastery
 
PerlMonks  

Re^4: scanning hash

by Aristotle (Chancellor)
on Aug 01, 2004 at 15:20 UTC ( #379090=note: print w/ replies, xml ) Need Help??


in reply to Re^3: scanning hash
in thread scanning hash

Oh dear. Next thing we will argue about whether the equality of two values can be determined by the equality of their string representations. :-)

Makeshifts last the longest.


Comment on Re^4: scanning hash
Re^5: scanning hash
by ysth (Canon) on Aug 02, 2004 at 19:50 UTC
    (puzzled) If you really want...I'll start us off.

    You can't determine the equality of two values from the equality of their string representations.

      To illustrate the point:

      $ perl -le '$a = $b = "foo"; print \$a eq \$b ? "true" : "false"' false

      The strings are identical, but they're two different strings. The string representations of references to them differ. Are they equal or not? This is a question of semantics that you can't answer without additional context.

      Indeed, if we just accept the string representation as the universal measure of equality, then ambrus is right: the empty string and undef are equal, and thus all of my arguing has been moot. However, experience tells me it is a prudent bet to assume that in most situations, undef needs to be treated differently from an empty string.

      Makeshifts last the longest.

        I was thinking of something simpler, such as:
        $x = 1.23456; $y = 1.234560000000001; print 0+($x == $y); # prints 0 for me print 0+($x eq $y); # prints 1 for me
        or
        $x = 0; $y = "0";
        Are they equal? Yes and no.

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://379090]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others lurking in the Monastery: (11)
As of 2015-07-03 09:01 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (50 votes), past polls