我如何验证值是Perl在阵列（列表）present？ [英] How can I verify that a value is present in an array (list) in Perl?

问题描述

我有可能值的列表：

  @a = QW（富巴巴兹）;
 

如何在一个简洁的方式将一个值 $ VAL 是present或缺如在检查 @a ？

这是显而易见的实现是遍历列表，但我相信 TMTOWTDI 。

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感谢所有谁回答！这三个答案，我想强调的：

1. 接受的答案 - 最内置和向后兼容的方​​式




2. <一个href=\"http://stackoverflow.com/questions/720482/how-to-verify-that-a-value-is-$p$psent-in-an-array-list-in-perl/720530#720530\">RET's回答是最干净的，但只有好为Perl 5.10及更高版本。




3. <一个href=\"http://stackoverflow.com/questions/720482/how-to-verify-that-a-value-is-$p$psent-in-an-array-list-in-perl/720812#720812\">draegtun's答案是（可能）快了一点，但使用一个额外的模块需要。我不喜欢添加依赖，如果我能避开他们，在这种情况下并不需要的性能差异，但如果你有1,000,000元列表中，您可能想给这个答案一试。

解决方案

Perl的grep的中储存卡（）函数是专门做这个。

  @matches =的grep（/ ^ $ MyItem /，@someArray）;
 

也可以插入任何Ex pression到匹配

  @matches = grep的（$ _ == $ VAL，@a）;
 

I have a list of possible values:

@a = qw(foo bar baz);

How do I check in a concise way that a value $val is present or absent in @a?

An obvious implementation is to loop over the list, but I am sure TMTOWTDI.

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Thanks to all who answered! The three answers I would like to highlight are:

1. The accepted answer - the most "built-in" and backward-compatible way.

2. RET's answer is the cleanest, but only good for Perl 5.10 and later.

3. draegtun's answer is (possibly) a bit faster, but requires using an additional module. I do not like adding dependencies if I can avoid them, and in this case do not need the performance difference, but if you have a 1,000,000-element list you might want to give this answer a try.

解决方案

Perl's bulit in grep() function is designed to do this.

@matches = grep( /^MyItem$/, @someArray );

or you can insert any expression into the matcher

@matches = grep( $_ == $val, @a );

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