???? ???

PHP?? ?????(')? ????(")? ???? ???? ?? ??? ????? ?? ?? ? ????? ?????? ??? ?????.

?????

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

• ' ?????? ?????
• \ ????? ????

$name = "John";
echo 'Hello $name'; // Output: Hello $name
echo 'I\'m learning PHP'; // Output: I'm learning PHP

????

????? ?? ????? ???? ????, ?? ??? ?? ??? ??? ??? ???? ?? ???? ????.

$name = "John";
echo "Hello $name"; // Output: Hello John
echo "Array value: {$array['key']}"; // Complex expressions need curly braces

??? ??? ??

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

$name = "John";
$iterations = 1000000;

// Test single quotes
$start = microtime(true);
for ($i = 0; $i < $iterations; $i++) {
    $string = 'Hello ' . $name;
}
$single_quote_time = microtime(true) - $start;

// Test double quotes
$start = microtime(true);
for ($i = 0; $i < $iterations; $i++) {
    $string = "Hello $name";
}
$double_quote_time = microtime(true) - $start;

printf("Single quotes: %.6f seconds\n", $single_quote_time);
printf("Double quotes: %.6f seconds\n", $double_quote_time);

? ??? ???? ????? ?? PHP ????? ??? ?????? ?? ? ? ????. ??? ? ?? ?? ??? ????.

1. ?? ????: ????? ?? ???? ????? PHP? ?? ????? ??? ??? ?? ???? ???? ???.
2. ??? ???: ? ?? ?? ?? ?? ??? ?? ???? ????? ????? ?? ?? ?? ????? ? ?? ???? ??? ? ????.

?? ??

1. ??? ?? ?? ?????? ?????.
   • ???? ??? ????
   • ?? ?? ? ???? ??? ????
   • ???? ?? ??? ???? ??? ??? ??

$sql = 'SELECT * FROM users WHERE status = "active"';
$html = '<div>



<ol>
<li>Use double quotes when:

<ul>
<li>You need variable interpolation</li>
<li>You need escape sequences like \n, \t, etc.
</li>
</ul>
</li>
</ol>

<pre class="brush:php;toolbar:false">$message = "Dear $userName,\nThank you for your order #$orderId";

??? ?

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

$user = [
    'name' => 'John',
    'age' => 30
];

// Single quotes require concatenation
$message1 = 'User ' . $user['name'] . ' is ' . $user['age'] . ' years old';

// Double quotes allow direct interpolation with curly braces
$message2 = "User {$user['name']} is {$user['age']} years old";

// Both produce the same output:
// User John is 30 years old

?? ?

1. ??? ?? ??? ???? ?? ?????? ???? ??? ???? ???.
2. ??? ??? ???? ?? ???? ??? ?? ????? ?????.
3. ?? ? ????? ???? ?? heredoc ?? nowdoc ??? ?? ???? ?? ????.
4. ??? ???? ???? ???. ??? ?? ???? ?? ???? ? ??? ??? ????.

? ??? ????? ? ????: ??? ?? ? ??? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!