I have a variable which always contains one of these two cases:
false
A number (it can be also 0)
My variable in reality is this:
$index = array_search(1, array_column($var, 'box'));
//=> the output could be something like these: false, 0, 1, 2, ...
Now I want to detect $index is false or anything else. How can I implement such a condition?
It should be noted none of these doesn't work:
if ( empty($index) ) { }
if ( !isset($index) ) { }
if ( is_null($index) ) { }
And I want this condition:
if ( ? ) { // $index is false } else { // $index is a number (even 0) }
You can use the PHP identical operator ===:
if (false === 0)
This will return false if they are of the same type. Unlike == where type juggling occurs, false is not identical to 0.
if ($index === false) {
// $index is false
} else {
// $index is a number (even 0)
}
More information on the difference between the identical operator === and the comparison operator ==: How do the PHP equality (== double equals) and identity (=== triple equals) comparison operators differ?
Use the === operator...
if(false == 0)
That will cast 0 to false and you get false == false
if(false === 0)
That does not cast and you get false compared to zero, which is not the same.
For not equal to, use !== instead of ===
Related
I'm new to PHP and I found in my code, when I pass a FALSE to a function. It converted to null immediately. I've read some articles knowing that False and null are equal. But I don't know when this conversion happens.
Below is my code
function equal($expected, $actual){
if($expected == $actual) { //... }
}
function foo(){
$signal = getSignal();
equal(FALSE, $signal->good); //...
}
You will need to use triple equal signs === for equality. For example
false == null; // true
false === null; // false
0 == false; // true
0 === false; // false
Check the docs on comparison operators
No, they are NOT converted. You can var_dump($variable) at any time to see both the type and the value of $variable any time. But there are a few things which evaluates to false with the == comparison operator. So in fact false == null will evaluate to true just as false == 0 or false == "0" in PHP. This is why the comparison operator === comes into the picture - using that instead of == in above example, all will evaluate to false instead of true.
For more information, see http://php.net/manual/en/language.operators.comparison.php
This question already has answers here:
How do the PHP equality (== double equals) and identity (=== triple equals) comparison operators differ?
(13 answers)
Closed 9 years ago.
In my case should I use != as below, or is !== more appropriate, what is the difference.
private function authenticateApi($ip,$sentKey) {
$mediaServerIp = '62.80.198.226';
$mediaServerKey = '45d6ft7y8u8rf';
if ($ip != $mediaServerIp ) {
return false
}
elseif ($sentKey != $mediaServerKey ) {
return false
}
else {
return true;
}
}
public function setVideoDeletedAction(Request $request)
{
//Authenticate sender
if ( $this->authenticateApi($request->server->get("REMOTE_ADDR"),$request->headers->get('keyFile')) != true ) {
new response("Din IP [$ip] eller nyckel [********] är inte godkänd för denna åtgärd.");
}
!= checks value
if($a != 'true')
!== checks value and type both
if($a !== 'true')
http://www.php.net/manual/en/language.operators.comparison.php
As the manual says, one compares type as well.
!== is more strict. '1'==1 returns true, but '1'===1 - false, because of different types.
=== and !== are used to compare objects that might be of different type. === will return TRUE iff the types AND values are equal; !== will return TRUE if the types OR values differ. It is sometimes known as the 'congruency' operator.
If you are comparing two things that you know will always be the same type, use !=.
Here's an example of using !==. Suppose you have a function that will return either an integer or the value FALSE in the event of a failure. 0 == FALSE, but 0 !== FALSE because they are different types. So you can test for FALSE and know an error happened, but test for 0 and know you got a zero but no error.
What does this !== mean in php and is there any doc's on it?
PHP comparison operators, "Not identical" (5th in the table)
This operator works much like != but also checks the type of the operands. For example:
3 != '3' is false, but 3 !== '3' is true.
== is the comparison operator you're familiar with: if two values are equivalent, they == each other. There's some type coercion that goes on before the comparison.
4 == '4' // true: equivalent value, different type
=== is a more strict comparison that requires that values be of the same type.
4 === 4 // true: same value, same type
'4' === '4' // true: same value, same type
4 === '4' // false: equivalent value, different type
!== is the opposite of the strict comparison operator, so it is true when two values are of a different type or different value or both.
4 !== 3 // true: different value, same type
4 !== '4' // true: equivalent value, different type
'4' !== 3 // true: different value, different type
'4' !== '3' // true: different value, same type
4 !== 4 // false: same value, same type
It means "not equal or not the same type".
This shows the difference between != and !==:
"5"!=5 //returns false
"5"!==5 //returns true
That is the not identical operator
$a !== $b
Returns TRUE if $a is not equal to $b, or they are not of the same type.
For example, it is used to check if a variable is false and not 0, since 0 is the same that false for PHP.
$bar = 0;
if ($bar != false) { echo '$bar != false'; } // won't output the text
if ($bar !== false) { echo '$bar !== false'; } // will output the text
!= is used for value only
but
!== is used for value and type both
suppose:
$a = "5"; // String
$b = 5; // Integer
$a!=$b // false
$a!==$b // true
That's the difference.
I saw
if($output !== false){
}
It's an exclamation mark with two equals signs.
It almost works like not equal. Does it has any extra significance?
They are the strict equality operators ( ===, !==) , the two operands must have the same type and value in order the result to be true.
For example:
var_dump(0 == "0"); // true
var_dump("1" == "01"); // true
var_dump("1" == true); // true
var_dump(0 === "0"); // false
var_dump("1" === "01"); // false
var_dump("1" === true); // false
More information:
PHP Comparison Operators
PHP’s === Operator enables you to compare or test variables for both equality and type.
So !== is (not ===)
!== checks the type of the variable as well as the value. So for example,
$a = 1;
$b = '1';
if ($a != $b) echo 'hello';
if ($a !== $b) echo 'world';
will output just 'world', as $a is an integer and $b is a string.
You should check out the manual page on PHP operators, it's got some good explanations.
See this question: How do the equality (==) and identity (===) comparison operators differ?.
'!==' is the strict version of not equal. I.e. it will also check type.
yes, it also checks that the two values are the same type. If $output is 0, then !== will return false, because they are not both numbers or booleans.
I have been programming in PHP for a while but I still dont understand the difference between == and ===. I know that = is assignment. And == is equals to. So what is the purpose of ===?
It compares both value and type equality.
if("45" === 45) //false
if(45 === 45) //true
if(0 === false)//false
It has an analog: !== which compares type and value inequality
if("45" !== 45) //true
if(45 !== 45) //false
if(0 !== false)//true
It's especially useful for functions like strpos - which can return 0 validly.
strpos("hello world", "hello") //0 is the position of "hello"
//now you try and test if "hello" is in the string...
if(strpos("hello world", "hello"))
//evaluates to false, even though hello is in the string
if(strpos("hello world", "hello") !== false)
//correctly evaluates to true: 0 is not value- and type-equal to false
Here's a good wikipedia table listing other languages that have an analogy to triple-equals.
It is true that === compares both value and type, but there is one case which hasn't been mentioned yet and that is when you compare objects with == and ===.
Given the following code:
class TestClass {
public $value;
public function __construct($value) {
$this->value = $value;
}
}
$a = new TestClass("a");
$b = new TestClass("a");
var_dump($a == $b); // true
var_dump($a === $b); // false
In case of objects === compares reference, not type and value (as $a and $b are of both equal type and value).
The PHP manual has a couple of very nice tables ("Loose comparisons with ==" and "Strict comparisons with ===") that show what result == and === will give when comparing various variable types.
It will check if the datatype is the same as well as the value
if ("21" == 21) // true
if ("21" === 21) // false
=== compares value and type.
== doesn't compare types, === does.
0 == false
evaluates to true but
0 === false
does not
Minimally, === is faster than == because theres no automagic casting/coersion going on, but its so minimal its hardly worth mentioning. (of course, I just mentioned it...)
It's a true equality comparison.
"" == False for instance is true.
"" === False is false