Perl Learning: 2.9. The while Control Structure

最新推荐文章于 2025-07-16 08:50:08 发布

原创最新推荐文章于 2025-07-16 08:50:08 发布 · 288 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#structure #perl #documentation #system

Perl 专栏收录该内容

72 篇文章

订阅专栏

本文详细介绍了Perl编程语言中的while循环结构，包括其基本语法、如何避免无限循环以及循环内部的操作流程。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

2.9. The while Control Structure

Like most algorithmic programming languages, Perl has a number of looping structures.^[] The while loop repeats a block of code as long as a condition is true:

^[] Every programmer eventually creates an infinite loop by accident. If your program keeps running and running, you can generally stop it in the same way you'd stop any other program on your system. Often, typing Ctrl-C will stop a runaway program; check with your system's documentation to be sure.

    $count = 0;
    while ($count < 10) {
      $count += 2;
      print "count is now $count/n"; # Gives values 2 4 6 8 10
    }

As always in Perl, the truth value here works like the truth value in the if test. Like the if control structure, the block curly braces are required. The conditional expression is evaluated before the first iteration, so the loop may be skipped completely if the condition is initially false.