PHP

<?php
class Person
{
    public $name = "unknown";
    public $city = "Bhopal";
    protected $salary = 0;
    public function greet() { return "Hello"; }
    public function walk() {}
}
class Teacher extends Person
{
    public $subject = "PHP";
    public function teach() {}
}
$t = new Teacher();
echo "class_exists('Teacher'): " . var_export(class_exists('Teacher'), true) . "<br>";
echo "get_class: " . get_class($t) . "<br>";
echo "get_parent_class: " . get_parent_class($t) . "<br>";
echo "get_class_methods: " . implode(", ", get_class_methods('Teacher')) . "<br>";
echo "get_class_vars: " . implode(", ", array_keys(get_class_vars('Teacher'))) . "<br>";
echo "get_object_vars: " . json_encode(get_object_vars($t)) . "<br>";
echo "method_exists(teach): " . var_export(method_exists($t, 'teach'), true) . "<br>";
echo "is_a(Person): " . var_export(is_a($t, 'Person'), true) . "<br>";
echo "is_subclass_of(Person): " . var_export(is_subclass_of($t, 'Person'), true) . "<br>";
echo "Number of declared classes: " . count(get_declared_classes());
?>

<?php
function addAll()
{
    $n = func_num_args();
    $args = func_get_args();
    return "$n arguments, first = " . func_get_arg(0) . ", sum = " . array_sum($args);
}
function welcome($name, $city) { return "Welcome $name from $city"; }

echo addAll(5, 10, 15) . "<br>";
echo call_user_func('welcome', 'Asha', 'Indore') . "<br>";
echo call_user_func_array('welcome', ['Ravi', 'Bhopal']) . "<br>";
echo "function_exists('welcome'): " . var_export(function_exists('welcome'), true) . "<br>";
echo "is_callable('strtoupper'): " . var_export(is_callable('strtoupper'), true) . "<br>";
$user = get_defined_functions()['user'];
echo "User-defined functions: " . implode(", ", $user) . "<br>";
register_shutdown_function(function () {
    echo "Shutdown function: script finished.";
});
echo "Last line of the script.<br>";
?>

<?php
mkdir("reports/2026/oct", 0777, true);          // recursive
file_put_contents("reports/2026/oct/sales.txt", "Sales: 1200");
file_put_contents("reports/2026/oct/stock.txt", "Stock: 340");
file_put_contents("reports/2026/summary.csv", "month,total");

echo "scandir('reports/2026'): " . implode(", ", scandir("reports/2026")) . "<br>";
echo "glob('reports/2026/oct/*.txt'): " . implode(", ", glob("reports/2026/oct/*.txt")) . "<br>";

$h = opendir("reports/2026/oct");
echo "readdir: ";
while (($entry = readdir($h)) !== false) {
    if ($entry != "." && $entry != "..") echo "$entry ";
}
closedir($h);
echo "<br>is_dir('reports'): " . var_export(is_dir("reports"), true) . "<br>";
echo "Current directory: " . basename(getcwd()) . "<br>";
echo "Free disk space: " . round(disk_free_space(".") / 1073741824, 1) . " GB<br>";

// clean up: files first, then directories
array_map('unlink', glob("reports/2026/oct/*.txt"));
unlink("reports/2026/summary.csv");
rmdir("reports/2026/oct"); rmdir("reports/2026"); rmdir("reports");
echo "After cleanup, is_dir('reports'): " . var_export(is_dir("reports"), true);
?>

<?php
file_put_contents("students.csv", "roll,name,city\n101,Asha,Bhopal\n102,Ravi,Indore\n");
$path = "/opt/lampp/htdocs/phpbook/ch25/students.csv";
echo "basename: " . basename($path) . "<br>";
echo "dirname: " . dirname($path) . "<br>";
echo "pathinfo extension: " . pathinfo($path, PATHINFO_EXTENSION) . "<br>";
echo "filesize: " . filesize("students.csv") . " bytes, filetype: " . filetype("students.csv") . "<br>";
echo "is_readable: " . var_export(is_readable("students.csv"), true) . "<br>";
echo "permissions: " . substr(sprintf('%o', fileperms("students.csv")), -4) . "<br>";
echo "fnmatch('*.csv'): " . var_export(fnmatch("*.csv", "students.csv"), true) . "<br>";

$h = fopen("students.csv", "r");
$header = fgetcsv($h);
echo "<b>" . implode(" | ", $header) . "</b><br>";
while (($row = fgetcsv($h)) !== false) {
    echo implode(" | ", $row) . "<br>";
}
echo "Pointer position at end: " . ftell($h) . "<br>";
rewind($h);
echo "After rewind: " . ftell($h) . "<br>";
fclose($h);

file_put_contents("settings.ini", "[database]\nhost = localhost\nuser = root\n[site]\ntitle = PHP Book\n");
$ini = parse_ini_file("settings.ini", true);
echo "parse_ini_file: host = {$ini['database']['host']}, title = {$ini['site']['title']}";
?>