<?php // Q1 $str = '$123,000.00A'; $length = strlen($str); $new_str = ''; for ($i = 0; $i < $length; $i++) { if (is_numeric($str{$i}) || in_array($str{$i}, [',', '.'])) { $new_str .= $str{$i}; } } echo '<pre>'; echo $new_str; echo '<hr>'; $replace_str = preg_replace('/[^(d|\,|.)*]/', '', $str); echo $replace_str; echo '<pre>'; // Q2 $arr = ['abcd', 'ad', 'a', 'abc']; $new_arr = array_map('strlen', $arr); $max_length = max($new_arr); $min_length = min($new_arr); echo 'max length is ' . $max_length . ' , min length is ' . $min_length; echo '<hr>'; // Q3 $url = 'http://www.example.com/demo/index.php?age=10'; echo 'Scheme:' . $_SERVER['REQUEST_SCHEME'], '<br>'; echo 'Host:' . $_SERVER['HTTP_HOST'], '<br>'; echo 'Pathinfo:' . $_SERVER['REQUEST_URI'], '<br>'; var_dump(parse_url($url)); // Q4 header('Location:http://www.baidu.com');