$re = '/[0-9]*(?=;0;0;6275)/';
$str = 'm[mi++]="28.01.17 18:20:00|623;0;8368|0;0;0;6275;0;0"
m[mi++]="28.01.17 18:15:00|623;0;8317|0;0;0;6275;0;0"
m[mi++]="28.01.17 18:10:00|652;0;8265|0;0;0;6275;0;0"';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php