PHP line breaks converter

convert-eol.php

<?php

/**
 * Converts a string using CR, LF, CRLF, or possibly a mix of these, to the given EOL character(s).
 *
 * @param string $text The text to convert.
 * @param string $eol  The line break character(s).
 *
 * @return string
 */
function convertEOL(string $text, string $eol) : string
{
    return str_replace(["\r\n", "\r", "\n"], ["\n", "\n", $eol], $text);
}

This is handy when line breaks are expected in a given format.
For example HTTP / MIME headers, mailto URLs, etc. only accept CRLF as per their respective RFCs.

Note that the order of the replacements above is important.