How Can I Match Newline Characters in PHP Regex Without Using [\\r\\n]?

Matching Newline Characters in PHP Regex without [rn]

In PHP, the regular expression [rn] is commonly used to match carriage returns (r) or linefeeds (n). However, what if you want to match these characters without using this specific pattern?

Unicode Newline Escape Sequence: R

PCRE introduces the R escape sequence, which by default matches Unicode newline sequences. These include:

• rn (CRLF)
• n (LF)
• r (CR)
• f (Form feed)
• x0b (Vertical tab)
• x85 (Next line)

Example:

<code class="php">$string = "
Test
";

if (preg_match('~\R~', $string)) {
  echo "Matched";
} else {
  echo "Not Matched";
}</code>

Unicode Newline Escape Sequence with 'u' Flag:

To match newline characters outside the ASCII range, enable the 'u' (unicode) flag:

<code class="php">preg_match('~\R~u', $string);</code>

Restricting R to CR, LF, or CRLF:

If you only want to match carriage returns, linefeeds, or both, use the following pattern:

<code class="php">preg_match('~(*BSR_ANYCRLF)\R~', $string);</code>

Additional Conventions for Newline Characters:

PCRE also supports various conventions for indicating newline characters:

• (*CR) - Carriage return
• (*LF) - Linefeed
• (*CRLF) - Carriage return, followed by linefeed
• (*ANYCRLF) - Any of the above three
• (*ANY) - All Unicode newline sequences

Note: R does not have special meaning inside a character class and instead acts as the literal character "R."

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