PHP - Operators
There are many operators used in PHP, so we have separated them intothe following categories to make it easier to learn them all.
- Assignment Operators
- Arithmetic Operators
- Comparison Operators
- String Operators
- Combination Arithmetic & Assignment Operators
Assignment Operators
Assignment operators are used to set a variable equal to a value or seta variable to another variable's value. Such an assignment of value is done with
the "=", or equal character. Example:
- $my_var = 4;
- $another_var = $my_var;
Arithmetic Operators
Operator | English | Example |
---|---|---|
+ | Addition | 2 + 4 |
- | Subtraction | 6 - 2 |
* | Multiplication | 5 * 3 |
/ | Division | 15 / 3 |
% | Modulus | 43 % 10 |
PHP Code:
$addition = 2 + 4; $subtraction = 6 - 2; $multiplication = 5 * 3; $division = 15 / 3; $modulus = 5 % 2; echo "Perform addition: 2 + 4 = ".$addition."<br />"; echo "Perform subtraction: 6 - 2 = ".$subtraction."<br />"; echo "Perform multiplication: 5 * 3 = ".$multiplication."<br />"; echo "Perform division: 15 / 3 = ".$division."<br />"; echo "Perform modulus: 5 % 2 = " . $modulus . ". Modulus is the remainder after the division operation has been performed. In this case it was 5 / 2, which has a remainder of 1.";
Display:
Perform addition: 2 + 4 = 6
Perform subtraction: 6 - 2 = 4
Perform multiplication: 5 * 3 = 15
Perform division: 15 / 3 = 5
Perform modulus: 5 % 2 = 1. Modulus is the remainder after the division operation has been performed.
In this case it was 5 / 2, which has a remainder of 1.
Perform subtraction: 6 - 2 = 4
Perform multiplication: 5 * 3 = 15
Perform division: 15 / 3 = 5
Perform modulus: 5 % 2 = 1. Modulus is the remainder after the division operation has been performed.
In this case it was 5 / 2, which has a remainder of 1.
Comparison Operators
Comparisons are used to check the relationship between variables and/orvalues. If you would like to see a simple example of a comparison operator in action, check out our
If Statement Lesson. Comparison
operators are used inside conditional statements and evaluate to either true
or false. Here are the most important comparison operators of PHP.
Assume: $x = 4 and $y = 5;
Operator | English | Example | Result |
---|---|---|---|
== | Equal To | $x == $y | false |
!= | Not Equal To | $x != $y | true |
< | Less Than | $x < $y | true |
> | Greater Than | $x > $y | false |
<= | Less Than or Equal To | $x <= $y | true |
>= | Greater Than or Equal To | $x >= $y | false |
String Operators
As we have already seen in the EchoLesson, the period "." is used to add two strings together, or more technically,
the period is the concatenation operator for strings.
PHP Code:
$a_string = "Hello"; $another_string = " Billy"; $new_string = $a_string . $another_string; echo $new_string . "!";
Display:
Hello Billy!
Combination Arithmetic & Assignment Operators
In programming it is a very common task to have to increment a variable by some fixed amount. Themost common example of this is a counter. Say you want to increment a counter by 1, you would
have:
- $counter = $counter + 1;
- $counter += 1;
combination operator is that it reduces code readability to those programmers who are not used to such
an operator. Here are some examples of other common
shorthand operators. In general, "+=" and "-=" are the most widely used combination operators.
Operator | English | Example | Equivalent Operation |
---|---|---|---|
+= | Plus Equals | $x += 2; | $x = $x + 2; |
-= | Minus Equals | $x -= 4; | $x = $x - 4; |
*= | Multiply Equals | $x *= 3; | $x = $x * 3; |
/= | Divide Equals | $x /= 2; | $x = $x / 2; |
%= | Modulo Equals | $x %= 5; | $x = $x % 5; |
.= | Concatenate Equals | $my_str.="hello"; | $my_str = $my_str . "hello"; |
Pre/Post-Increment & Pre/Post-Decrement
This may seem a bit absurd, but there is even a shorter shorthand for the commontask of adding 1 or subtracting 1 from a variable. To add one to a variable or "increment"
use the "++" operator:
- $x++; Which is equivalent to $x += 1; or $x = $x + 1;
- $x--; Which is equivalent to $x -= 1; or $x = $x - 1;
want to increment before the line of code is being executed or after the
line has executed. Our PHP code below will display the difference.
PHP Code:
$x = 4; echo "The value of x with post-plusplus = " . $x++; echo "<br /> The value of x after the post-plusplus is " . $x; $x = 4; echo "<br />The value of x with with pre-plusplus = " . ++$x; echo "<br /> The value of x after the pre-plusplus is " . $x;
Display:
The value of x with post-plusplus = 4
The value of x after the post-plusplus is = 5
The value of x with with pre-plusplus = 5
The value of x after the pre-plusplus is = 5
As you can see the value of $x++ is not reflected in the echoed text because The value of x after the post-plusplus is = 5
The value of x with with pre-plusplus = 5
The value of x after the pre-plusplus is = 5
the variable is not incremented until after the line of code is executed. However,
with the pre-increment "++$x" the variable does reflect the addition immediately.
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