$re = '`(src="cid:).*?(.+?(\.gif|\.png|\.jpg))+?([^"]*)`';
$str = 'bodyHtmlText:
<p class=MsoNormal><a href="http://www.centric.eu/craft"><span style=\'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;text-decoration:none\'><img border=0 width=300 height=100 id="_x0000_i1026" src="cid:image001.jpg@01D2E5DE.EC0337E0" alt="cid:image002.jpg@01D19BE7.F4CB9B70"></span></a><span style=\'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D\'> <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style=\'font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D\'><o:p> </o:p></span></p><p class=MsoNormal><a href="https://www.facebook.com/Centric"><span style=\'color:blue;text-decoration:none\'><img border=0 width=31 height=75 id="_x0000_i1027" src="cid:image002.jpg@01D2E5DE.EC0337E0" alt="Like ons"></span></a><span lang=EN-US style=\'color:#1F497D\'> </span><a href="http://www.linkedin.com/company/centric"><span style=\'color:blue;text-decoration:none\'>
USAGE:
const string patternImageFilesInBody = @"(src=""cid:).*?(.+?(\\.gif|\\.png|\\.jpg))+?([^""]*)";
//const string patternImageFilesInBody = @"(src=""cid:).*?/?([^/]+?(\\.gif|\\.png|\\.jpg))+?(@[^""]*)";
//const string patternImageFilesInBody = @"(src=\\""cid:).*?/?([^/]+?(\\.gif|\\.png|\\.jpg))+?(@.................)";
var bodyIndependentsoft = Regex.Replace(bodyHtmlText, patternImageFilesInBody, m => "src=\\"" + tempFolder + "/" + m.Groups[2].Value + "\\"");
';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($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