Operators in PHP

Operators in PHP

When comparing or processing variables and other values you use operators. Without them, PHP would be more of a word jumble instead of a language. In some unique cases, operators slightly alter the relationship between two variables or their function within PHP. Without further adieu,
here they are..

Basic Operators
Add ( + ): $a = 1; $a = $a + 5; // $a is equal to 6
Subtract ( - ): $s = 10; $s = $s - 5; // $s is equal to 5
Multiply ( * ): $m = 2; $m = $m * 10; // $m is equal to 20
Divide ( / ): $d = 20; $d = $d / 5; // $d is equal to 4
Modulus ( % ) Provides the remainder after division:
$u = 5; $u = $u % 2; // $u is equal to 1

Assignment Operators
Add ( += ): $a = 1; $a += 5; // $a is equal to 6
Subtract ( -= ): $s = 10; $s -= 5; // $s is equal to 5
Multiply ( *= ): $m = 2; $m *= 10; // $m is equal to 20
Divide ( /= ): $d = 20; $d /= 5; // $d is equal to 4
Modulus ( %= ) Provides the remainder after division:
$u = 5; $u %= 2; // $u is equal to 1
Concatenate ( .= ) Join onto the end of a string:
$c = 5; $c .= 2; // $c is now a string, '52'
See Also:
Concatenate – Join together in succession

Comparison Operators
Greater Than ( > ): 2 > 1
Less Than ( < ): 1 < 2
Greater Than or Equal To ( >= ): 2 >= 2 3 >= 2
Less Than or Equal To ( <= ): 2 <= 2 2 <= 3

Short-Hand Plus or Minus one
Also known as:
Increment ( $integer++; )
Decrement ( $integer--; )
Example:
$a = 1;
$a = $a + 1; // $a is now equal to 2
$a++; // $a is now equal to 3
$a--; // $a is now equal to 2 again, same as $a = $a – 1;

@ - Suppress Errors
Placing the commercial at symbol (@) before a function tells PHP to suppress
any errors generated by that function.
Examples:
include('DoesNotExist.txt');
Warning: include(DoesNotExist.txt) [function.include]: failed to open
stream: No such file or directory
@include('DoesNotExist.txt');
// blank output below because the error was suppressed

& - Pass by Reference
References allow two variables to refer to the same content. In other words,
a variable points to its content (rather than becoming that content). Passing
by reference allows two variables to point to the same content under
different names. The ampersand ( & ) is placed before the variable to be
referenced.
Examples:
$a = 1;
$b = &$a; // $b references the same value as $a, currently 1
$b = $b + 1; // 1 is added to $b, which effects $a the same way
echo "b is equal to $b, and a is equal to $a";
b is equal to 2, and a is equal to 2