How to Effectively Replace Newline Styles in PHP?

How to Replace Newline Styles in PHP

In PHP, dealing with different newline styles can be a challenge. To replace all newlines ('rn', 'n', 'r') with 'rn', the following methods can be used:

preg_replace() with R

This method utilizes a regular expression to match all Unicode newline sequences (regardless of OS):

$string = preg_replace('~\R~u', "\r\n", $string);

If you want to match only CRLF newlines:

$string = preg_replace('~(*BSR_ANYCRLF)\R~', "\r\n", $string);

Note:

• R represents any Unicode newline sequence.
• BSR_ANYCRLF limits R to only match CR, LF, or CRLF.
• u specifies that the input string should be treated as UTF-8.

PCRE Options for R

PCRE offers options to customize R behavior:

• PCRE_BSR_ANYCRLF: Restricts R to match only CR, LF, or CRLF.
• PCRE_BSR_UNICODE: Enables R to match any Unicode newline sequence.

Special Pattern Sequences

Alternatively, you can specify R matching behavior in the pattern itself:

• (*BSR_ANYCRLF): Match CR, LF, or CRLF only.
• (*BSR_UNICODE): Match any Unicode newline sequence.

Example:

$pattern = '(*BSR_ANYCRLF)\R';
preg_replace($pattern, "\r\n", $string);

These special sequences must be placed at the beginning of the pattern in uppercase and can override the options set with pcre_compile().

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