$re = '/\|\|(.*?)\|\|/m';
$str = 'About ||PrimarySchool|| % of children in ||Country|| attend primary school. ||SecondarySchoolFemale|| % of girls and ||SecondarySchoolMale|| % of boys finish secondary school. Literacy is ||LiteracyFemale|| % for females and ||LiteracyMale|| % for males.';
preg_match_all($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