Руководство по PHP
Пред.	Глава 10. Operators	След.

Comparison Operators

Comparison operators, as their name implies, allow you to compare two values. You may also be interested in viewing the type comparison tables, as they show examples of various type related comparisons.

Таблица 10-4. Comparison Operators

Example	Name	Result
$a == $b	Equal	`TRUE` if $a is equal to $b.
$a === $b	Identical	`TRUE` if $a is equal to $b, and they are of the same type. (PHP 4 only)
$a != $b	Not equal	`TRUE` if $a is not equal to $b.
$a <> $b	Not equal	`TRUE` if $a is not equal to $b.
$a !== $b	Not identical	`TRUE` if $a is not equal to $b, or they are not of the same type. (PHP 4 only)
$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.

Another conditional operator is the "?:" (or ternary) operator.


<?php
// Example usage for: Ternary Operator
$action = (empty($_POST['action'])) ? 'default' : $_POST['action'];

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

The expression (expr1) ? (expr2) : (expr3) evaluates to expr2 if expr1 evaluates to TRUE, and expr3 if expr1 evaluates to FALSE.

See also strcasecmp(), strcmp(), Array operators, and the manual section on Types.

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Bitwise Operators	Уровень выше	Error Control Operators