Detailed explanation of the use of PHP function in_array()

PHP has a system function is_array() that can determine whether a value is in an array.
The syntax is as follows:

in_array(value,array,type)
return boolen

Parameter description:
value: the value to be searched
array: the array being searched
type: type, true congruent, false non-congruent (default)

Example 1: Normal use

Code:

$str = 1;
 
$arr = array(1,3,5,7,9);
 
$boolvalue = in_array($str,$arr);
 
var_dump($boolvalue);

Execution result:

bool(true)

Example 2: Using the third parameter
Non-congruent
Code:

$str = '1';
 
$arr = array(1,3,5,7,9);
 
$boolvalue = in_array($str,$arr,false);
 
var_dump($boolvalue);

Execution result:

bool(true)

Congruent
Code:

$str = '1';
 
$arr = array(1,3,5,7,9);
 
$boolvalue = in_array($str,$arr,true);
 
var_dump($boolvalue);

Execution result:

bool(false)

Example 3: Clone object
Code:

class a {
    public $a = 1;  
    public function fun(){
        return $this->a; 
    }
}
 
class b {
    public $a = 2;  
    public function fun(){
        return $this->a; 
    }
}
 
$a = new a();
$b = new b();
 
$c = clone $a;
 
$arr = array($a,$b);
 
$boolvalue = in_array($c,$arr,false);
 
var_dump($boolvalue);

Execution result:

bool(true)

Code:

class a {
    public $a = 1;  
    public function fun(){
        return $this->a; 
    }
}
 
class b {
    public $a = 2;  
    public function fun(){
        return $this->a; 
    }
}
 
$a = new a();
$b = new b();
 
$c = clone $a;
 
$arr = array($a,$b);
 
$boolvalue = in_array($c,$arr,true);
 
var_dump($boolvalue);

Execution result:

bool(false)

Example 4: Multidimensional array
Code:

$str = 10;
 
$arr = array(
    array(1,2,3,4),
    array(5,6,7,8,9),
    10
);
 
$boolvalue = in_array($str,$arr);
 
var_dump($boolvalue);

Execution result:

bool(true)

Code:

$str = 10;
 
$arr = array(
    array(1,2,3,4),
    array(5,6,7,8,9,10),
);
 
$boolvalue = in_array($str,$arr);
 
var_dump($boolvalue);

Execution result:

bool(false)

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