Perl:从 <> 读取

Question

从 <> 读取什么？在 Perl 中做什么？例如，下面会做什么？

print for(<>);

Answer 1

所谓的菱形运算符 (<>) 从 STDIN 或指定为命令行参数的文件名中逐行读取(在标量上下文中)。

来自 perldoc perlop :

The null filehandle <> is special: it can be used to emulate the behavior of sed and awk. Input from <> comes either from standard input, or from each file listed on the command line. Here's how it works: the first time <> is evaluated, the @ARGV array is checked, and if it is empty, $ARGV[0] is set to "-", which when opened gives you standard input. The @ARGV array is then processed as a list of filenames.

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在列表上下文中，<>返回所有行，每行存储为列表中的一个元素。

这意味着print for <>;将做与 print while <>; 相同的事情, 尽管有更多的内存。