Comparison Operators

Comparison operators, as their name implies, allow you to compare two values.

表格 11-4. 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, which operates as in C and many other languages.

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