php, regex, preg_match

[gintare]

I am getting errors in preg_match:

1) "preg_match() expects parameter 4 to be long, string given".

<?php
 
$desc= "th793; D. A. Melnick; Zinc Oxide Photoconduction, an Oxygen Adsorption; J. Chem. Phys., 26, (1957), p1136; doi:10.1063/1.1743483; http://jcp.aip.org/resource/1/jcpsa6/v26/i5/p1136_s1 Donald A. Melnick ;;FROM RCONCL;; _nowdatebk: 2015-01-10 10:26:28.575267 ;";
 
preg_match("/doi/i", $desc, $matches, 'PCRE_DOTALL' );
 
print_r($matches);
 
?>

2) The preg_match does not find string "doi:10.1063/1.1743483"

<?php
$desc= "th793; D. A. Melnick; Zinc Oxide Photoconduction, an Oxygen Adsorption; J. Chem. Phys., 26, (1957), p1136; doi:10.1063/1.1743483; http://jcp.aip.org/resource/1/jcpsa6/v26/i5/p1136_s1 Donald A. Melnick ;;FROM RCONCL;; _nowdatebk: 2015-01-10 10:26:28.575267 ;";
 
preg_match("/doi.*;/i", $desc, $matches, 'PCRE_DOTALL' );
 
print_r($matches);
?>

I have checked the official documentation:
http://php.net/manual/en/function.preg-match.php
http://php.net/manual/en/regexp.reference.dot.php

The code is working if i am not using constant 'PCRE_DOTALL'. But, i believe in some cases i may need search through several lines, thus i asked the questions above.

Thanks in advance!

[Rabbit]

The error message is pretty clear. The fourth parameter needs to be a numeric data type, not a string. You have supplied the string instead of the constant named PCRE_DOTALL. 'PCRE_DOTALL' is a string, PCRE_DOTALL is the name of a constant that has a defined numeric value.