无涯教程-Perl - Switch语句函数

switch语句允许根据值列表测试变量的相等性。每个值称为一个case，并且为每个switch case检查正在打开的变量。

Switch 语法

perl编程语言中switch语句的概要如下所示:-

use Switch;
switch(argument) {
case 1            { print "number 1" }
case "a"          { print "string a" }
case [1..10,42]   { print "number in list" }
case (@array)    { print "number in list" }
case /\w+/{ print "pattern" }
case qr/\w+/{ print "pattern" }
case (%hash)     { print "entry in hash" }
case (&sub)      { print "arg to subroutine" }
else              { print "previous case not true" }
}

Switch 流程图

Switch 示例

#!/usr/local/bin/perl
use Switch;
$var=10;
@array=(10, 20, 30);
%hash=(key1 => 10, key2 => 20);
switch($var) {
case 10           { print "number 100\n" }
case "a"          { print "string a" }
case [1..10,42]   { print "number in list" }
case (@array)    { print "number in list" }
case (%hash)     { print "entry in hash" }
else              { print "previous case not true" }
}

执行上述代码时，将生成以下输出-

number 100

但是，现在考虑一个下面情况，我们将使用Next将控件转移到下一个匹配的情况，在本示例中是一个列表-

#!/usr/local/bin/perl
use Switch;
$var=10;
@array=(10, 20, 30);
%hash=(key1 => 10, key2 => 20);
switch($var) {
case 10           { print "number 100\n"; next; }
case "a"          { print "string a" }
case [1..10,42]   { print "number in list" }
case (@array)    { print "number in list" }
case (%hash)     { print "entry in hash" }
else              { print "previous case not true" }
}

执行上述代码时，将生成以下输出-

number 100
number in list

参考链接

www.learnfk.com/perl/perl-s…