revision:
code:
<?php
$a = "Hello world!";
$b = 'Hello world!';
echo $a;
echo "<br>";
echo $b;
?>
<br><br>
<?php
$c = 5985;
var_dump($c);
echo "<br>";
$d = 10.365;
var_dump($d);
echo "<br>";
$cars = array("Volvo","BMW","Toyota");
var_dump($cars);
?>
<br><br>
<?php
class Car {
public $color;
public $model;
public function __construct($color, $model) {
$this->color = $color;
$this->model = $model;
}
public function message() {
return "My car is a " . $this->color . " " . $this->model . "!";
}
}
$myCar = new Car("black", "Volvo");
echo $myCar -> message();
echo "<br>";
$myCar = new Car("red", "Toyota");
echo $myCar -> message();
?>
<br><br>
<?php
$e = "Hello world!";
$e = null;
var_dump($e);
?>
code:
<?php
$is_email_valid = false;
var_dump($is_email_valid);
echo "<br>";
$is_submitted = true;
var_dump($is_submitted);
?>
code:
<?php
$title = "PHP string is awesome";
echo strlen($title)."<br>";
echo $title[0]."<br>";
echo $title[11]."<br>";
echo strlen("What a wonderful world!");
echo "<br>";
echo str_word_count("What a wonderful world!");
echo "<br>";
echo strrev("What a wonderful world!");
echo "<br>";
echo strpos("What a wonderful world!", "world");
echo "<br>";
echo str_replace("world", "place", "What a wonderful world!");
echo "<br>";
$name = "Walter";
echo "Hello {$name}";
? >
code:
<?php
$email = null;
var_dump($email);
echo "<br>";
var_dump(is_null($email));
echo "<br>";
$home = "www.lwitters.com";
var_dump(is_null($home));
?>
code:
<y;?php
// Check if the type of a variable is integer
$f = 5985;
var_dump(is_int($f));
echo "< br>";
// Check again...
$f = 59.85;
var_dump(is_int($f));
// Check if the type of a variable is float
echo "< br>";
$g = 10.365;
var_dump(is_float($g));
echo "< br>";
// Check if a numeric value is finite or infinite
$h = 1.9e411;
var_dump($h);
echo "< br>";
// Invalid calculation will return a NaN value
$j = acos(8);
var_dump($j);
echo "< br>";
// Check if the variable is numeric
$k = 5985;
var_dump(is_numeric($k));
echo "< br>";
$l = "5985";
var_dump(is_numeric($l));
echo "< br>";
$m = "59.85" + 100;
var_dump(is_numeric($m));
echo "< br>";
$n = "Hello";
var_dump(is_numeric($n));
echo "< br>";
// Cast float to int
$o = 23465.768;
$int_cast = (int)$o;
echo $int_cast;
echo "< br>";
// Cast string to int
$p = "23465.768";
$int_cast = (int)$p;
echo $int_cast;
?>
code:
<?php
echo(pi());
echo "< br>";
print(pi());
echo "< br>";
echo(min(0, 150, 30, 20, -8, -200) . "< br>");
echo(max(0, 150, 30, 20, -8, -200) . ":< br>");
echo(abs(-6.7) . "< br>");
echo(sqrt(64) . "< br>");
print(round(0.60) . "< br>");
echo(round(0.49) . "< br>");
echo(round(0.50) . "< br>");
echo((rand()) . "< br>");
echo(rand(10, 100) . "< br>");
?>
Type casting allows you to convert a value of one type to another. To cast a value, use the following type casting operators:
(array): array;
(bool) or (boolean): boolean;
(int) or (integer): integer;
(object): object;
(real), (double), or (float): float;
(string): string.
code:
<?php
echo (int)12.5 . '<br>'; // 12
echo (int)12.1 . '<br>'; // 12
echo (int)12.9 . '<br>'; // 12
echo (int)-12.9 . '<br>'; // -12
$message = 'Hi';
$num = (int) $message;
echo $num."<br>"; // 0
$amount = (int)'100 USD';
echo $amount."<br>"; // 100
$qty = null;
echo (int)$qty."<br>"; // 0
$amount = (float)100;
echo $amount."<br>"; // 100
$amount = 100;
echo (string)$amount . " USD"."<br>"; // 100 USD
$amount = 100;
echo $amount . ' USD'."<br>"; // 100 USD
$is_user_logged_in = true;
echo (string)$is_user_logged_in."<br>"; // 1
$numbers = [1,2,3];
$str = (string) $numbers;
echo $str."<br>"; // Array
?>
PHP is a loosely typed programming language: when you define a variable, you don't need to declare a type for it. Internally, PHP will determine the type by the context in which you use the variable.
PHP has a feature called type juggling, which means that during the comparison of variables of different types, PHP will convert them to the common, comparable type.
code:
<?php
$qty = 20;
if($qty == '20') {
echo 'Equal';
}
print "<br>";
$total = 100;
$qty = "20";
$total = $total + $qty;
echo $total; // 120
print "<br>";
?>