??

PHP? null ??? ?? ???? ?? ??? ?????. ?? ??? ????? ??? ?? ??? ????? ???? ? ???? ?? ??? ?????. null? ?? ??? ?? ????? ???? ??? ???? ?? PHP?? ??? ???? ??? ???? ? ??????.

---

PHP?? null? ??????

PHP??? ??? ?? ?? ??? null? ?????.

• ?? null? ???????.
• ?? ???? ?????.
• unset() ??? ???? ??? ??????.

?:

<?php
$var1 = null;  // Assigned null value explicitly
$var2;         // No value assigned
unset($var3);  // Variable has been unset

var_dump($var1); // Output: NULL
var_dump($var2); // Output: NULL
var_dump($var3); // Output: NULL
?>

---

? ??? ??

• null? ????? ???? ???? null, NULL, NuLl? ?? ???? ?????.
• ? ??? ???? ??? ????.
• is_null() ??? ???? ??? null?? ??? ? ????.

---

null ? ??

??? null?? ????? is_null() ??? ????? ===? ??? ??? ??? ??? ? ????.

is_null() ?? ?:

<?php
$var = null;

if (is_null($var)) {
    echo "The variable is null.";
}
?>

??? ??(===)? ??? ?:

<?php
$var = null;

if ($var === null) {
    echo "The variable is null.";
}
?>

---

?? null ?

??? ?????? ?? ???? ?? ?? PHP? ???? ?? ??? null ??? ?????.

?:

<?php
$var;  // Declared but not assigned a value
var_dump($var);  // Output: NULL
?>

---

?? ?? ??

unset() ??? ??? ???? ? ?????. unset()? ???? ??? null? ???.

?:

<?php
$var = 10;
unset($var);

var_dump($var);  // Output: NULL
?>

---

????? null ??

?? ?????? null? false? ?????. ?, if ??? null? ???? ??? ?? ??? ??? ? ????.

?:

<?php
$var = null;

if (!$var) {
    echo "The variable is null or false.";
}
?>

---

null ?? ???(??)? ???? ??? ??

PHP 7?? ??? null?? ???? null?? ???? ??? ? ?? null ?? ???(??)? ???????.

?:

<?php
$username = null;

// If $username is null, use "Guest" as the default value
echo $username ?? "Guest";  // Output: Guest
?>

? ??? ?? ???? ?? ??? ???? ???? ??? ? ?? ?????.

---

PHP?? null? ?? ???? ?? ??

---

?? ???

??? ?? ?? ?? ?? ? ??? ????? ?????? null? ?????.

$response = null;  // Will be assigned a value later

---

? ???

?? ?? ????? ? ?? ???? ??? ????? null? ?????.

<?php
$var1 = null;  // Assigned null value explicitly
$var2;         // No value assigned
unset($var3);  // Variable has been unset

var_dump($var1); // Output: NULL
var_dump($var2); // Output: NULL
var_dump($var3); // Output: NULL
?>

---

??? ??? ????

???? ??? ????? ????? null? ?????.

<?php
$var = null;

if (is_null($var)) {
    echo "The variable is null.";
}
?>

---

??

PHP? null ??? ?? ??? ???? ?? ?????. ?? ????? ??? ?????, ? ??? ????, ??? ????? ???? ? ??? ? ????. null? ???? ??? ???? ?? ???? ?? ?? ??? ???? ? ??? ???. ???? ?? ??? ???? null ?? ???? ???? null ??? ??? ?? PHP ??? ????? ? ???? ?????.

? ??? PHP ?? ?? - NULL? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!