w3resource

PHP: Array Operators

Description

This is a Comprehensive PHP array operators tutorial from w3resource.com

List of array operators

Name Example Result
Union $x + $y Union of $x and $y. The + operator appends elements of remaining keys from the right-sided array to the left-handed, but duplicated keys are not overwritten.
Equality $x == $y TRUE if $x and $y have the same key/value pairs.
Identity $x === $y TRUE if $x and $y have the same key/value pairs in the same order and of the same types.
Inequality $x != $y TRUE if $x is not equal to $y.
Inequality $x <> $y TRUE if $x is not equal to $y.
Non-identity $x !== $y TRUE if $x is not identical to $y.

Example : array union (+) operator

In the following example, the union operator adds the last element from the $b array ($c = $a + $b) with $a array as "c=>" key is not present in $a array. In the second statement ($c = $b + $a) no element is added from $b as all the keys of $a array are present in $b array.

<?php 
$a = array("a" => "apple", "b" => "banana");
$b = array("a" => "pear", "b" => "strawberry", "c" => "cherry");
$c = $a + $b; // Union of $a and $b
echo "Union of \$a and \$b : <br />";
var_dump($c);
$c = $b + $a; // Union of $b and $a 
echo "<br />Union of \$b and \$a : <br />";
var_dump($c);
?>

Output:

Union of $a and $b: 
array(3) {    ["a"]=>    string(5) "apple"    ["b"]=>    string(6) "banana"    ["c"]=>    string(6) "cherry"  } 
Union of $b and $a :
array(3) {    ["a"]=>    string(4) "pear"    ["b"]=>    string(10) "strawberry"    ["c"]=>    string(6) "cherry"  }

View the example in the browser

Example : array equality (==) and identity(===) operators

In the following example equality operator returns true as the two arrays have same key/value pairs whereas identity operator returns false as the key/value of the comparing arrays are same but not in same order. 

<?php
$a = array("1" => "apple", "0" => "banana");
$b = array( "banana", "apple");
var_dump($a == $b);
var_dump($a === $b);
?>

Output: 

bool(true)  bool(false)

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Next: Incrementing Decrementing Operators



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PHP: Tips of the Day

PHP: How to get a variable name as a string in PHP?

You could use get_defined_vars() to find the name of a variable that has the same value as the one you're trying to find the name of. Obviously this will not always work, since different variables often have the same values, but it's the only way I can think of to do this.

Edit: get_defined_vars() doesn't seem to be working correctly, it returns 'var' because $var is used in the function itself. $GLOBALS seems to work so I've changed it to that.

function print_var_name($var) {
    foreach($GLOBALS as $var_name => $value) {
        if ($value === $var) {
            return $var_name;
        }
    }

    return false;
}

Edit: to be clear, there is no good way to do this in PHP, which is probably because you shouldn't have to do it. There are probably better ways of doing what you're trying to do.

Ref : https://bit.ly/37qFimU