gaojinguan 发表于 2017-5-17 08:41:17

perl switch case

  Below shows how to emulate the switch... case ... construct in C
  


# file:
#   switch_emu.pl
# description:
#   this is the file to show how to simulate the switch ... case ... construct in Perl
#
# conclusion:
#    perl does not have switch case...
#    You can emulate switch ... case with bare blocks and label
#
use strict;
SWITCH:
{
if (/^abc/) { $abc =1; last SWITCH; }
if (/^def/) { $def =1; last SWITCH; }
if (/^xyz/) { $xyz =1; last SWITCH; }
$nothing = 1;
}

SWITCH1:
{
/^abc/       && do { $abc =1; last SWITCH1; }
/^def/       && do { $def =1; last SWITCH1; }
/^xyz/       && do { $xyz =1; last SWITCH1; }
$nothing = 1
}
if (/^abc/)    { $abc = 1}
elsif (/^def/) { $def = 1 }
elsif (/^def/) { $def = 1 }
else         { $nothing = 1 }

# the last in the do { } blocks does not exit the do {} block ,
# but rather exit the for loop
for ($very_nasty_long_name[$i++][$j++]->method()) {
/this pattern/   and do { push @flags, '-e'; last; };
/that pattern/   and do { push @flags, '-h'; last; };
/something else/ and do {                  last; };
die "unknown value: '$_'";
}
 
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