Perl switch statement

A switch statement allows you to test when a variable is equal to more than one value. Each value is called a case, and the variable being tested checks each switch case.

Switch case execution is based on the Switch module, which is performed using Filter::Util::Call and Text::Balanced, both of which need to be installed.

Grammar

The syntax format looks like this:

use Switch;

switch(argument){
   case 1            { print "数字 1" }
   case "a"          { print "字符串 a" }
   case [1..10,42]   { print "数字在列表中" }
   case (\@array)    { print "数字在数组中" }
   case /\w+/        { print "正则匹配模式" }
   case qr/\w+/      { print "正则匹配模式" }
   case (\%hash)     { print "哈希" }
   case (\&sub)      { print "子进程" }
   else              { print "不匹配之前的条件" }
}

Here are the rules for the switch statement:

You can use any type of standard argument in the parentheses of a switch statement.
You can have any number of case statements in a switch. Each case is followed by a value to compare and a colon.
The calibration after the case statement is compared to the stum of the switch statement to determine whether it is equal.
When the variable being tested is equal to the constant in case, the statement followed by case is executed until a break statement is encountered.
The switch statement can have an optional else, which is executed at the end, and the statement executes in the event that all case mismatches.
When case is matched, the case statement block code is executed and the switch statement jumps out after execution.
When the case is matched, if we need to continue with the next case statement, we need to add the next statement.

Flow chart

Perl switch statement

Instance

#!/usr/bin/perl

use Switch;

$var = 10;
@array = (10, 20, 30);
%hash = ('key1' => 10, 'key2' => 20);

switch($var){
   case 10           { print "数字 10\n" }
   case "a"          { print "字符串 a" }
   case [1..10,42]   { print "数字在列表中" }
   case (\@array)    { print "数字在数组中" }
   case (\%hash)     { print "在哈希中" }
   else              { print "没有匹配的条件" }
}

The above procedure is performed and the output is:

数字 10

Let's look at an example that uses next:

#!/usr/bin/perl

use Switch;

$var = 10;
@array = (10, 20, 30);
%hash = ('key1' => 10, 'key2' => 20);

switch($var){
   case 10           { print "数字 10\n"; next; }  # 匹配后继续执行
   case "a"          { print "string a" }
   case [1..10,42]   { print "数字在列表中" }
   case (\@array)    { print "数字在数组中" }
   case (\%hash)     { print "在哈希中" }
   else              { print "没有匹配的条件" }
}

The above procedure is performed and the output is:

数字 10
数字在列表中

Perl conditional statement

Perl switch statement

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