正则表达式和preg_replace

Question

这一行是什么意思：

$fields = explode("\r\n", preg_replace('/\x0D\x0A[\x09\x20]+/', ' ', $header));

我从这个答案中得到了cURL , get redirect url to a variable

Answer 1

preg_replace将展开电子邮件header lines that are split across multiple lines。然后explode调用将结果字符串拆分为一个数组，每个数组单元有一个标题行。

例如，字符串：

Subject: This is a long subject
    line split across
  multiple lines
From: user@example.com

将由preg_replace转换为：

Subject: This is a long subject line split across multiple lines
From: user@example.com

以下explode会给您：

Array(
    [0] => 'Subject: This is a long subject line split across multiple lines',
    [1] => 'From: user@example.com'
)