# Perl 中的`given-when-default`语句 > 原文： [https://beginnersbook.com/2017/02/given-when-default-statement-in-perl/](https://beginnersbook.com/2017/02/given-when-default-statement-in-perl/) 正如我在[上一篇文章](https://beginnersbook.com/2017/02/switch-case-in-perl/)中所讨论的那样，`switch-case`在 Perl 5 中被弃用。三个新关键字：`given-when-default`在 Perl 5 中引入，提供类似于`switch case`的功能。 #### 语法： ```perl given (argument) { when (condition) { statement(s); } when (condition) { statement(s); } when (condition) { statement(s); } . . . default { statement(s); } } ``` #### 例： ```perl #!/usr/local/bin/perl use v5.10; no warnings 'experimental'; printf "Enter any number:"; $num = <STDIN>; given($num){ when ($num>10) { printf "number is greater than 10\n"; } when ($num<10) { printf "number is less than 10\n"; } default { printf "number is equal to 10\n"; } } ``` **输出：** ```perl Enter any number:10 number is equal to 10 ```