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<?php
$response = 'youtube("asdadada", "123")';
// function parameters
/*preg_match('/([\w\_\d]+)\(([\w\W]*)\)/', $response, $matches);
print_r("fctname " . $matches[1]);
$params = explode(",", $matches[2]);
print_r("PARAMS ");
print_r($params);*/
// match a single character
$str = "Jack is a boy";
preg_match('/a/', $str, $matches);
print_r("<strong>Single character /a/</strong><br>");
print_r($matches);
print_r("<br><br>");
// CHARACTER CLASSES
// mathches only one out of serveral characters
print_r("<strong>Single character /J[a]ck/</strong><br> " . $str);
preg_match_all('/J[a]ck/', $str, $matches);
print_r($matches);
print_r("<br>");
$str = "Jeck is a boy";
print_r("<strong>Single character /J[ae]ck/</strong><br> " . $str);
preg_match_all('/J[ae]ck/', $str, $matches);
print_r($matches);
print_r("<br><br>");
// match ranges
$str = "Jack is a boy";
print_r("<strong>Match single character in range /J[a-z]ck/</strong><br> " . $str);
print_r("<br>");
preg_match_all('/J[a-z]ck/', $str, $matches);
print_r($matches);
print_r("<br><br>");
// negate character class
$str = "Jack is a boy";
print_r("<strong>Negate character class /J[^b]ck/</strong><br> " . $str);
print_r("<br>");
preg_match_all('/J[^b]ck/', $str, $matches);
print_r($matches);
print_r("<br><br>");
// shorthand character classes
// Match single character digit
$str = "Jack 1 is a boy";
print_r("<strong>Match single character digit /\d/</strong><br> " . $str);
print_r("<br>");
preg_match_all('/\d/', $str, $matches);
print_r($matches);
print_r("<br><br>");
// Match a word (alphanumeric plus underscore only)
$str = "Jack is a boy$";
print_r("<strong>Match a word (alphanumeric plus underscore only) /\w/</strong><br> " . $str);
print_r("<br>");
preg_match_all('/\w/', $str, $matches);
print_r($matches);
print_r("<br><br>");
// Match a word boundary (alphanumeric plus underscore only)
// if it is on a boundary like /b /b
$str = "Jack4 is a 4boy ";
print_r("<strong>Match a word boundary /\b/</strong><br> " . $str);
print_r("<br>");
preg_match_all('/\b4/', $str, $matches);
print_r($matches);
$str = "Jack4 is a boy 44";
print_r("<br><br>");
// Match whitespace character
// other : \t - tab, \r - carriage return, \n - line feed, \a - bell, \e - escape etc
$str = "Jack is a boy$";
print_r("<strong>Match whitespace character /\s/</strong><br> " . $str);
print_r("<br>");
preg_match_all('/\s/', $str, $matches);
print_r($matches);
print_r("<br><br>");
// Match any character (almost)
$str = "Jack and Jaek is a boy$";
print_r("<strong>Match any character (almost) /Ja.k/</strong><br> " . $str);
print_r("<br>");
preg_match_all('/Ja.k/', $str, $matches);
print_r($matches);
print_r("<br><br>");
// ANCHORS
// match position - start or end
// ^ matches at the start of the string
// $ matches at the end of the string
$str = "Jack and Jaek is a boy$";
print_r("<strong>Match any character (almost) /Ja.k/</strong><br> " . $str);
print_r("<br>");
preg_match_all('/^J/', $str, $matches);
print_r($matches);
print_r("<br><br>");
// REPETITION
// The question mark makes the preceding token in the regular expression optional
$str = "Jack and Jak is a boy$";
print_r("<strong>preceding token in the regular expression optional /Jac?k/</strong><br> " . $str);
print_r("<br>");
preg_match_all('/Jac?k/', $str, $matches);
print_r($matches);
print_r("<br><br>");
// The * tells the engine to attempt to match the preceding token ZERO or more times
$str = "Jack and Jak is a boy <1>";
print_r("<strong>* tells the engine to attempt to match the preceding token ZERO or more times /[^y]<[A-Za-z0-9]*>/</strong><br> " . $str);
print_r("<br>");
preg_match_all('/[^y]<[A-Za-z0-9]*>/', $str, $matches);
print_r($matches);
print_r("<br><br>");
// The + tells the engine to attempt to match the preceding token once or more
$str = "Jack and Jak is a boy <1> <>";
print_r("<strong>+ tells the engine to attempt to match the preceding token ONCE or more /<[A-Za-z0-9]+>/</strong><br> " . $str);
print_r("<br>");
preg_match_all('/<[A-Za-z0-9]+>/', $str, $matches);
print_r($matches);
print_r("<br> versus * (zero or more)");
preg_match_all('/<[A-Za-z0-9]*>/', $str, $matches);
print_r($matches);
print_r("<br><br>");
// The {} specify a specific amount of repetition {min,max}
$str = "1111 999999";
print_r("<strong>The {} specify a specific amount of repetition /<[A-Za-z0-9]+>/</strong><br> " . $str);
print_r("<br>");
// what is this,
// [1-9] - only once since number can't start with 0
// [0-9] - repeat minum 3 maximum 4 times
preg_match_all('/[1-9][0-9]{3,4}/', $str, $matches);
print_r($matches);
print_r("<br><br>");
?>
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