equality test for multiple variables

[Matt Garrish]

Just curious if anyone has a more elegant way to check whether multiple
values are equal. For example, given:

$a = $b = $c = $d = $e = 'test';

is there anything better than:

if ( ($a eq $b) && ($b eq $c) && ($c eq $d) && ($d eq $e) ) { ... }

It would be nice (cleaner) if you could simply test if $a eq $b eq $c eq $d,
but that obviously won't work.

Matt

 

[Uri Guttman]

MG> Just curious if anyone has a more elegant way to check whether multiple
MG> values are equal. For example, given:

MG> $a = $b = $c = $d = $e = 'test';

MG> is there anything better than:

MG> if ( ($a eq $b) && ($b eq $c) && ($c eq $d) && ($d eq $e) ) { ... }

MG> It would be nice (cleaner) if you could simply test if $a eq $b eq
MG> $c eq $d, but that obviously won't work.

use List::Util ;

min( $a, $b, $c, $d, $e ) == max( $a, $b, $c, $d, $e ) ;

uri

 

[Joe Smith]

MG> Just curious if anyone has a more elegant way to check whether multiple
MG> values are equal. For example, given:

MG> $a = $b = $c = $d = $e = 'test';

MG> is there anything better than:

MG> if ( ($a eq $b) && ($b eq $c) && ($c eq $d) && ($d eq $e) ) { ... }

MG> It would be nice (cleaner) if you could simply test if $a eq $b eq
MG> $c eq $d, but that obviously won't work.

use List::Util ;

min( $a, $b, $c, $d, $e ) == max( $a, $b, $c, $d, $e ) ;

I expect that you meant to post this instead:

minstr( $a, $b, $c, $d, $e ) eq maxstr( $a, $b, $c, $d, $e ) ;

-Joe

 

[Eugene Mikheyev]

use List::Util ;

I expect that you meant to post this instead:

minstr( $a, $b, $c, $d, $e ) eq maxstr( $a, $b, $c, $d, $e ) ;

You really think this is more elegant? And, of course, this is fast...

 

[gnari]

Just curious if anyone has a more elegant way to check whether multiple
values are equal. For example, given:

$a = $b = $c = $d = $e = 'test';

is there anything better than:

if ( ($a eq $b) && ($b eq $c) && ($c eq $d) && ($d eq $e) ) { ... }

It would be nice (cleaner) if you could simply test if $a eq $b eq $c eq $d,
but that obviously won't work.

if you know that the strings do not contain say, ':', you can use:

if ("$a:"x4 eq "$b:$c:$d:$e:") {...}

gnari

 

[Anno Siegel]

You really think this is more elegant? And, of course, this is fast...

Elegant? It's about correct vs. incorrect.

Anno

 

[Eugene Mikheyev]

Elegant? It's about correct vs. incorrect.

Don't get me wrong. One of them has mistyped, other one has corrected his
mstake, but in general, my statement was something like "this test for
equality is even less <elegant> as Matt's"

 

[Anno Siegel]

Just curious if anyone has a more elegant way to check whether multiple
values are equal. For example, given:

$a = $b = $c = $d = $e = 'test';

is there anything better than:

if ( ($a eq $b) && ($b eq $c) && ($c eq $d) && ($d eq $e) ) { ... }

It would be nice (cleaner) if you could simply test if $a eq $b eq $c eq $d,
but that obviously won't work.

A hash can do it:

my %h;
@h{ $a, $b, $c, $d, $e} = ();
if ( keys %h == 1 ) { ... }

This doesn't need an external module, but Uri's suggestion using List::Util
is about twice as fast.

Anno

 

[Joe Smith]

You really think this is more elegant? And, of course, this is fast...

No, I was pointing out that the OP use 'eq' (to compare strings) as
opposed to '==' (to compare numbers), therefor min()==max() was not
the correct answer.
-Joe

 

[Matt Garrish]

A hash can do it:

my %h;
@h{ $a, $b, $c, $d, $e} = ();
if ( keys %h == 1 ) { ... }

This doesn't need an external module, but Uri's suggestion using List::Util
is about twice as fast.

Thanks to everyone for the suggestions! It's code I'm hoping not to be
responsible for for long so the cleaner (clearer) it is to read the
better... : )

Matt

 

[Anno Siegel]

Thanks to everyone for the suggestions! It's code I'm hoping not to be
responsible for for long so the cleaner (clearer) it is to read the
better... : )

In that case, if you're using one of the less obvious solutions,
make it a named sub. Here is a grep-based one:

sub all_equal { not ( @_ and grep $_[ 0] ne $_, @_) }

That one's a little faster than the hash, but still 15% slower than
the List::Util solution.

Anno

 

[Peter Scott]

Just curious if anyone has a more elegant way to check whether multiple
values are equal. For example, given:

$a = $b = $c = $d = $e = 'test';

is there anything better than:

if ( ($a eq $b) && ($b eq $c) && ($c eq $d) && ($d eq $e) ) { ... }

It would be nice (cleaner) if you could simply test if $a eq $b eq $c eq $d,
but that obviously won't work.

use Quantum::Superpositions;
if ( all($a, $b, $c, $d) eq $e ) ...

Couldn't resist...