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php Operators:

Operators are one of the important feature of every language. In php operators are classified in following categories:

Name	Symbol	Example	Output/Meaning
assignment	=	$x=2	assigns 2 into x
combined operator (addition)	+=	let $x=2 $x+=2	value of x will be 4
combined operator (subtraction)	-=	let $x=2 $x-=2	value of x will be 0
combined operator (multiplication)	*=	let $x=3 $x*=2	value of x will be 6
combined operator (division)	/=	let $x=2 $x/=2	value of x will be 1
combined operator (modulus)	%=	let $x=2 $x%=2	value of x will be 0

Name	Symbol	Example	Output/Meaning
And	and	$x and $y	true if both are true
Or	or	$x or $y	true if at least one is true
Xor	xor	$x xor $y	true if both equal, false if both unequal
Not	!	! $a	returns true if variable is false, and vice versa
And	&&	$a && $b	true if both are true
Or	\|\|	$a \|\| $b	true if at least one variable is true

Name	Symbol	Example	Output/Meaning
Concatenation Operator	. (Period symbol)	let $a="Hello", $b="World" $a.$b	HelloWorld
Concatenating Assignment Operator	.=	let $a="Hello", $a.="World"	HelloWorld

Name	Symbol	Example	Output/Meaning
Error control operator	@	$var=@$array['name'];	will not generate any error message if index 'name' is not present

Name	Symbol	Example	Output/Meaning
backticks	``	`ls -l`	this operator is used to execute shell commands, the output can be stored in a variable also.

Let us consider the following arrays:

$a=array("lang"=>"Java", "platform"=>"Cross");

$b=array("lang"=>"php", "platform"=>"Cross", "Year"=>"1995");

Name	Symbol	Example	Output/Meaning
Union	+	$a + $b	Array ( [lang] => php [paradigm] => imperative [Year] => 1995 )
Equality	= =	$a = = $b	(Since both are unequal, no output will be generated)
Identity	= = =	$a = = = $b	(Since both are unequal, no output will be generated)
Inequality	!=	$a != $b	1 (Since both are unequal)
Inequality	<>	$a <> $b	1 (Since both are unequal)
Non-identity	!= =	$a != = $b	1 (Since both are unequal)

In this example let us consider the following case:

<?php

class First{}

class Second{}

$a=new First();

print_r($a instanceof First);

print_r($a instanceof Second);

Name	Symbol	Example	Output/Meaning
instanceof	instanceof	AS ABOVE	1 (Since $a is the instance of class First) and On the second line nothing will be generated as $a is not the instance of class Second

php Operators