Operators


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Operators are used to manipulate or perform operations on variables and values.

Many operators are used in PHP, such as:-.

  • Assignment Operators
  • Arithmetic Operators
  • Comparison Operators
  • String Operators
  • Combination Arithmetic & Assignment Operators

Assignment Operators

They are used to set a variable equal to a value or set a variable to another variable's value.

Such an assignment of value is done with the "=", or equal character. Example:

  • $my_variable = 18;
  • $another_variable = $my_variable

Now both $my_variable and $another_variable contain the value 18. Assignments can also be used in conjunction with arithmetic operators.

Arithmetic Operators

Operator English Example
+ Addition 2 + 4
- Subtraction 6 - 2
* Multiplication 5 * 3
/ Division 15 / 3
% Modulus 43 % 10
PHP Code:
<?php

$addition = 2 + 4;
$subtraction = 6 - 2;
$multiplication = 5 * 3;
$division = 15 / 3;
$modulus = 5 % 2;

echo "Perform addition: 2 + 4 = ".$addition;
echo "Perform subtraction: 6 - 2 = ".$subtraction;
echo "Perform multiplication: 5 * 3 = ".$multiplication;
echo "Perform division: 15 / 3 = ".$division;
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.]

Comparison Operators

Comparison operators are used to check the relationship between variables and/or values.

Comparison operators are used inside conditional statements and evaluate to either true or false.

Important comparison operators of PHP are:-

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

There is only one string operator. ["." the period]

It is used to add two strings together, or more technically, the period is the concatenation operator for strings.

PHP Code:
<?php

$x_string = "Hello";
$y_string = " Cindy";
$output_string = $x_string . $y_string;

echo $output_string . "!";

?>
Display:
Hello Cindy!

Combination Arithmetic & Assignment Operators

In programming, various increasing or decreasing counters are used.

Say you want a counter that increase by 1,

  • $number = $number + 1;

However, there is a shorthand for doing this.[combination assignment/arithmetic operator that would accomplish the same task]

  • $number += 1;

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

There is an even shorter way for 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;

To subtract 1 from a variable, or "decrement" use the "--" operator:

$x--;

Which is equivalent to $x -= 1; or $x = $x - 1;

In addition to this you can specify whether you want the increment to be:-

  • Before code is being executed.
  • After the line has executed.
Example code below will display the difference.
PHP Code:
<?php

$x = 4;
echo "The value of x with post-plusplus = " . $x++;
echo "The value of x after the post-plusplus is " . $x;

$x = 4;
echo "The value of x with with pre-plusplus = " . ++$x;
echo "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

The value of $x++ is not reflected in the echoed text because the variable is not incremented until after the line of code is executed.

But, with the pre-increment "++$x" the variable does reflect the addition immediately.

Note
For more detail please see Php Manual at http://www.php.net

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