We've seen how the "=" sign works when we set variables in the
scripts we've written so far (as in the code $FavoriteColor = "blue";
and $utterance = "I will smite you!"; ). The equal sign
here is what we call the "assignment operator" and is the simplest
operator we've got: $a = b means "the variable a is assigned
the value b (for the moment)."
But you can squeeze a lot more juice out of your PHP using what are called
"comparison operators," "logical operators," and "arithmetic
operators." Here's what they are, in tables copied verbatim from PHP.net.
Comparison Operators
These give you the ability to compare whether elements are equal, identical,
less than or greater than one another (with some other variations).
| 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. |
Logical Operators
Here you can compare elements using comparisons and, or, and the like.
| Example |
Name |
Result |
| $a and $b |
And |
TRUE if both $a and $b are TRUE. |
| $a or $b |
Or |
TRUE if either $a or $b is TRUE. |
| $a xor $b |
Xor |
TRUE if either $a or $b is TRUE, but not both. |
| ! $a |
Not |
TRUE if $a is not TRUE. |
| $a && $b |
And |
TRUE if both $a and $b are TRUE. |
| $a || $b |
Or |
TRUE if either $a or $b is TRUE. |
Aritmetic Operators
Just what it says — this is basic math.
| Example |
Name |
Result |
| $a + $b |
Addition |
Sum of $a and $b. |
| $a - $b |
Subtraction |
Difference of $a and $b. |
| $a * $b |
Multiplication |
Product of $a and $b. |
| $a / $b |
Division |
Quotient of $a and $b. |
| $a % $b |
Modulus |
Remainder of $a divided by $b. |
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