[]=

php! 연산자

$a == $b	Equal	TRUE if $a is equal to $b after type juggling.
$a === $b	Identical	TRUE if $a is equal to $b, and they are of the same type.
$a != $b	Not equal	TRUE if $a is not equal to $b after type juggling.
$a <> $b	Not equal	TRUE if $a is not equal to $b after type juggling.
$a !== $b	Not identical	TRUE if $a is not equal to $b, or they are not of the same type.
$a < $b	Less than	TRUE if $a is strictly less than $b.
$a > $b	Greater than	TRUE if $a is strictly greater than $b.
$a <= $b	Less than or equal to	TRUE if $a is less than or equal to $b.
$a >= $b	Greater than or equal to	TRUE if $a is greater than or equal to $b.
$a <=> $b	Spaceship	An integer less than, equal to, or greater than zero when $a is less than, equal to, or greater than $b, respectively. Available as of PHP 7.

php??

// Example usage for: Null Coalesce Operator
$action = $_POST['action'] ?? 'default';

// The above is identical to this if/else statement
if (isset($_POST['action'])) {
    $action = $_POST['action'];
} else {
    $action = 'default';
}

php=>

PHP =>
  //The double arrow operator, => 
  //Used as an access mechanism for arrays.
  //The left side will have a corresponding value on the right side in array. 
  //This can be used to set values into a corresponding index of an array. 
  //The index can be a string or number.
$myArray = array(
    0 => 'Red',
    1 => 'Orange',
    2 => 'Yellow',
    3 => 'Green'
);

->php 에서

// Create a new instance of MyObject into $obj
$obj = new MyObject();
// Set a property in the $obj object called thisProperty
$obj->thisProperty = 'Fred';
// Call a method of the $obj object named getProperty
$obj->getProperty();

<?php
echo "Hello world";

// ... more code

echo "Last statement";

// the script ends here with no PHP closing tag

숫자보다 작은 경우 php

<?php
if ($a > $b)
  echo "a is bigger than b";
?>

php 는

<?php
echo "Hello World";
?>

->php 에서

// Create a new instance of MyObject into $obj
$obj = new MyObject();
// Set a property in the $obj object called thisProperty
$obj->thisProperty = 'Fred';
// Call a method of the $obj object named getProperty
$obj->getProperty();

php?:

// Example usage for: Ternary Operator
$action = $_POST['action'] ?: 'default';

// The above is identical to this if/else statement
if (empty($_POST['action'])) {
    $action = 'default';
} else {
    $action = $_POST['action'];
}