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PHP (PHP (Basics (Variables, functions (Expressions & Operators (For…

- - - - class Person {
        public $name="";
        protected $email;//only access in child class
        private $salary;
        }
        
        Print an object:
        $person = new Person();
        var_dump($person);
        
        Convert an Object to JSON:
        $jsonPerson = json_encode($person);
        echo $jsonPerson;
        
        Call a method:
        $person->get_email();//OR
        echo $person->get_email();
        
        Print a property:
        echo $person->name;
        echo $person->email;//Error access "protected"
        
        Static property:
        class Employee...{
        public static $base_salary=10;
        }
        
        Static method:
        class Employee..{
        public static function a_static_method() {
        return self::$base_salary * 85/100;
        }
        }
        
        Call a static method:
        Employee::a_static_method();
        
        Access static property:
        echo Employee::$base_salary;
        
        Inheritance:
        class Engineer extends Person {
        //Can access $email, $name
        }
        
        Setter:
        class...{
        public function set_email($new_email) {
        $this->email = $new_email;
        }
        }
        
        Define a method/function:
        class Engineer... {
        public function get_name(){
        return $this->name;
        }
        }
        
        Getter:
        class...{
        public function get_email(){
        return $this->name;
        }
        }
        
        Initiate an Object with Constructor:
        class Employee {
        public function __contruct() {...}
        }
        
        Constructor with params:
        public function __construct($email, $name) {
        $this->email = $email;
        $this->name = $name;
        }
        
        call a Constructor:
        $employee = new Employee('abc@gmail.com', "Hoang");
        
        Remove an Object:
        unset($objectA);
        
        When an object is removed, this is called:
        public function __destructor() {...}
    - - foreach($persons as $person) {...}
      - Append elements:
        $names = array();
        array_push($names, "Hoang");
        array_push($names, 12, 33);
        
        Print an array:
        print_r($arrayA);
        
        Merge 2 arrays:
        $array3 = array_merge($array1, $array2);
        
        Convert string to array:
        explode('.', $file_name);
        
        Last element in an array:
        end($names)
        
        Number of elements in an array:
        $fruits = array("orange", "lemon", "apple");
        $number_of_elements = count($fruits);
        
        Find an element in an array:
        in_array("Hoang", $names)
        
        Reverse an array:
        $fruits2 = array_reverse($fruits);
        
        Sort an array:
        sort($fruits);
        Reverse sort: rsort($fruits);
        
        Associative Array:
        $person = array("name"=>"Hoang", "age" => 25);
        $person["email"] = "....";
        
        "Key" can be a Number:
        $department = array (1 => 'Accounts', 2 => 'Economics'');
        echo $department[1];
        
        Sort an Associative Array:
        asort($person);//Sort by value
        
        Sort reverse: arsort(...);
    - - Print a string:
        In .php file:<body>
        <?php
        echo "Hello world";
        ?>
        </body>
        
        $str = "Hello";
        
        Convert string to lowercase:
        strtolower($full_name)
        
        Generate a string:
        uniqid('', true);
        uniqid('Hoang'); //Hoang2a3xjhee...
        
        Shuffle(hoán vị) characters:
        $str = "1234abcd!)(";
        $random_str = str_shuffle($str);
        
        Encrypt pass:
        $encrypted_password = sha1('mypass');
        
        String Concatenation:
        echo "my name: $name";
        
        Another way:
        echo "my name: ".$name;
        
        Reference to a variable:
        $name = "Hoang";
        $name2 = &$name;
      - Define a constant(no $):
        define("NAME": "John Smith");
        
        Environment variables:
        echo $_SERVER['SERVER_NAME'];
        Others:
        SERVER_NAME
        SERVER_PORT
        HTTP_USER_AGENT
        HTTP_FROM
        
        Cookie(save in Client):
        echo $_COOKIE['name'];
      - function multiply($x, $y) {
        return $x + $y;
        }
        ...
        Call: multiple(2,3);
        
        "global" variable:
        $x = 10;
        function fA() {
        $global $x = 2;
        }
        => $x = 2;
        
        Modulus:
        $x = 5;
        $remainder = $x%2;
        
        Identical:
        $x = 2;
        $y = 2;
        if ($x === $y) => ?
        
        Equal:
        $x = 2;
        $y = "2";
        if($x == $y) => ?
        
        Multiple conditions
        if (($x > 1) && ($x<10) || (x != 5)) {...}
        
        Multiple conditions
        if (($x > 1) and ($x<10) or (x != 5)) {...}
        
        Mathematical functions:
        $x = abs(-100);//absolute
        round(99.6); //100
        sqrt(100); //10
      - Expressions & Operators
        
        Ternary operator
        
        $x = 2;
        $x = ($x < 5) ? 5 : $x
        
        Unary Operators
        
        NOT: !
        Increment: ++
        Decrement: --
        
        if(x != 3) {...}
        ++$x;
        $x--
        
        check null:
        $a = null; //$a = NULL;
        //is_null($a) => true
        
        For loop:
        for($n=0;$n<10;$n++) {...}
        
        $day = 1;
        switch($day) {
        case 1: {...break;}
        ...
        default:
        echo "...";
        }
        
        In loop, we use:
        break; //exit for/while loop
        continue;//goto next loop
    - - 1.Download XAMPP, install.
        2.Open XAMPP, start MySQL, Apache, open Config
        3.Open httpd.conf, search DocumentRoot, change to Code Folder
        
        Option1
        Click Apache, Config, open httpd.conf
        
        Modify DocumentRoot to your local code:
        DocumentRoot "d:/code/AptechPHP"
        
        Save httpd.conf, restart Apache
        
        Option2:
        Start server using PHP(open in terminal):
        C:\xampp\php\php.exe -S localhost:82 -t D:\abc\
        82 = Port(82, 83, ...)
        D:\abc = your code folder
  - - - Perform Regex:
        if(preg_match_all('/Hoang/', $input_string, $array_result)) {...}
        
        Replace using Regex:
        $output_string = preg_replace('/Hoang/', 'John', $input_text);
        //Replace 'Hoang' by 'John'
        
        $result = preg_match('/Hoang/', $input_string);
        //1 or 0
        
        /I.*fine/ => Ex: I am fine
        
        /D.*/ => Ex: Daniel, Danish, Duck,...
        
        /[^abc]/ => "NOT" /[abc]/
        
        /[abc]/ => String contains "a" or "b" or "c"
        
        /D{2, }/ => Eg: DD, DDD, DDDD,...
    - - $file = $_FILES["file"];
        print_r($file);
        
        Upload:
        move_uploaded_file($tmp, 'uploads/ab.png')
        
        Redirect to another page:
        header("Location: ../index.php?signup=error")
        exit();
        
        Find multiple files:
        glob('uploads/cat*');
        
        Delete a file:
        if(unlink('uploads/a.jpg')){...success}
        Check: file_exists('uploads/a.jpg')
      - Button "Choose file":<input type="file" name="file"... Add more button below: <button name="submit"...>
    - - Button to submit:<button type="submit" name="submit">
        </button>
        
        Session: In abc.php
        <?php
        session_start();
        ?>
        <?php
        $_SESSION['isLoggedIn'] = 1;
        ?>
        
        Remove all sessions:
        session_unset();
        session_destroy();
      - Check pressing "submit" button:
        if(isset[$_POST["submit"]]) {....}
        
        Super globals, get params from GET, POST:
        $email = $_GET["email"];
        ...
        $age = $_POST["age"];
        
        Check variables:
        if(empty($first_name) || empty($last_name)){...}
  - - - $connection = mysqli_connect(
        $hostname,
        $user_name,//Eg: root
        $password,
        $db_name);
        
        Query
        
        Check result:
        if(mysqli_num_rows($result) > 0) {...}
        
        while($row = mysqli_fetch_assoc($result)) {
        echo $row["name"];
        }
        
        Insert, update, delete data
        
        $name = mysqli_real_escape_string($connection, $name);
        $sql = "INSERT INTO ...";
        $result = msqli_query($conn, $sql);
    - - Need connection string & create PDO object:
        
        Query/insert data with PDO(must use try..catch, binding, prepare, statement):
        
        Allow try...catch with PDOException:
        
        Then use try...catch
        
        Get result object: