| Example | Name | Result |
|---|
| $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 int less than, equal to, or greater than zero when $a is less than, equal to, or greater than $b, respectively. |
<?php
var_dump(0 == "a"); // 0 == 0 -> true
var_dump("1" == "01"); // 1 == 1 -> true
var_dump("10" == "1e1"); // 10 == 10 -> true
var_dump(100 == "1e2"); // 100 == 100 -> true
switch ("a") {
case 0:
echo "0";
break;
case "a": // never reached because "a" is already matched with 0
echo "a";
break;
}
?>
<?php
// Integers
echo 1 <=> 1; // 0
echo 1 <=> 2; // -1
echo 2 <=> 1; // 1
// Floats
echo 1.5 <=> 1.5; // 0
echo 1.5 <=> 2.5; // -1
echo 2.5 <=> 1.5; // 1
// Strings
echo "a" <=> "a"; // 0
echo "a" <=> "b"; // -1
echo "b" <=> "a"; // 1
echo "a" <=> "aa"; // -1
echo "zz" <=> "aa"; // 1
// Arrays
echo [] <=> []; // 0
echo [1, 2, 3] <=> [1, 2, 3]; // 0
echo [1, 2, 3] <=> []; // 1
echo [1, 2, 3] <=> [1, 2, 1]; // 1
echo [1, 2, 3] <=> [1, 2, 4]; // -1
// Objects
$a = (object) ["a" => "b"];
$b = (object) ["a" => "b"];
echo $a <=> $b; // 0
$a = (object) ["a" => "b"];
$b = (object) ["a" => "c"];
echo $a <=> $b; // -1
$a = (object) ["a" => "c"];
$b = (object) ["a" => "b"];
echo $a <=> $b; // 1
// not only values are compared; keys must match
$a = (object) ["a" => "b"];
$b = (object) ["b" => "b"];
echo $a <=> $b; // 1
?>
Related
