Conrad, Bill (ThomasTech) wrote:
> $Bill Luebkert wrote
>
>
>>Paul Rogers wrote:
>>
>>>What's the simplest/shortest way to write an IF statement given that I'm
>>>looking for the variable to be one of 5 possible choices?
>>>
>>>E.g.,
>>>
>>>if ($x eq 'a' or $x eq 'b' or $x eq 'c or $x eq 'd' or $x eq 'e') {
>>> blah
>>>}
>>>
>>>I guess what I'm asking for is if there is a way to simplify/shorten this
>
>
>>>structure?
>>
>>You could use a RE, but it may be slower :
>>
>>if ($x =~ /^[abcde]$/) {
>> code
>>
>>if the characters were words :
>>
>>if ($x =~ /^(word1|word2|word3|word4)$/) {
>> code
>
>
> I always thought that RE was faster. In light of this, which of the
> following is better
>
> if ( $test =~ /^Start of text/so ) {
>
> or
>
> if ( substr ( $text , 0 , 13 ) eq 'Start of text' ) {
What are you lazy ? :) Try benchmarking it yourself.
use Benchmark qw(cmpthese);
# my $text = "Start of text - some more text\n";
# my $text = "Start of text - some more text Start of text - some more text\n";
my $text = "Start of text - some more text Start of text - some more text Start
of text - some more text Start of text - some more text\n";
my $count = 5000000;
my $x = 0;
cmpthese ($count, {
'RE' => sub {
if ($text =~ /^Start of text/) {
$x++;
}
},
'substr' => sub {
if (substr ($text, 0, 13) eq 'Start of text') {
$x++;
}
},
}
);
__END__
I tried 3 different lengths of $text and substr is the clear winner.
Short string:
Rate RE substr
RE 969556/s -- -72%
substr 3443526/s 255% --
Longer string:
Rate RE substr
RE 955292/s -- -70%
substr 3168568/s 232% --
Longest string:
Rate RE substr
RE 916926/s -- -70%
substr 3076923/s 236% --
--
,-/- __ _ _ $Bill Luebkert Mailto:[EMAIL PROTECTED]
(_/ / ) // // DBE Collectibles Mailto:[EMAIL PROTECTED]
/ ) /--< o // // Castle of Medieval Myth & Magic http://www.todbe.com/
-/-' /___/_<_</_</_ http://dbecoll.tripod.com/ (My Perl/Lakers stuff)
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