Array Function in PHP

PHP provides various array functions to access and manipulate the elements of array. The important PHP array functions are given below.

Extract()

The extract() function to extract data from arrays and store it in variables.
This function uses array keys as variable names and values as variable values. For each element it will create a variable in the current symbol table.
This function returns the number of variables extracted on success.

Syntax:

extract(array)

Example:

<?php 
	$color=array('red'=>1,'black'=>2,'green'=>3); 
	extract($color); 
	echo $red;
?>

list()

list() function is also used to extract variables from an array.

list() is used with index array and associative array with numeric key.

For Example : Index array

<?php 
	$color=array("red","black","green"); 
	list($a,$b,$c) = $color; 
	echo "value of a:$a "; 
	echo "value of b:$b "; 
	echo "value of c:$c "; 
?>

Compact()

This function is opposite of extract() function.
It returns an array with all the variables added to it.
The compact() functions create associative array whose key value are the variable name and whose values are the variable values.

Example:

<?php 
	$var1="PHP"; 
	$var2="JAVA"; 
	$var3=compact("var1","var2"); 
	print_r($var3); 
?>

implode()

The implode() function returns a string from the elements of an array.
The implode() function accept its parameters in either order. However, for consistency with explode(), you should use the documented order of arguments.
The separator parameter of implode() is optional. However, it is recommended to always use two parameters for backwards compatibility.

Syntax:

implode(separator, array)

separator Optional. Specifies what to put between the array elements. Default is "" (an empty string)
array Required. The array to join to a string

Example: Join array elements with a string.

<?php 
	$arr = array('Hello','World!','Beautiful','Day!'); 
	echo implode(" ",$arr); 
	// Output: Hello World! Beautiful Day!
?>

explode()

The explode() function breaks a string into an array.
The "separator" parameter cannot be an empty string.

Syntax:

explode(separator, string, limit)

separator Required. Specifies where to break the string

string Required. The string to split
limit Optional. Specifies the number of array elements to return. Possible values:
- Greater than 0 - Returns an array with a maximum of limit element(s)
- Less than 0 - Returns an array except for the last limit elements()
- 0 - Returns an array with one element

Example: Break a string into an array.

<?php 
	$str = "Hello world. It's a beautiful day."; 
	print_r (explode(" ", $str));
	// Output: Array ( [0] => Hello [1] => world. [2] => It's [3] => a [4] => beautiful [5] => day. )
?>

array_flip()

The array_flip() function flips/exchanges all keys with their associated values in an array.

Syntax:

array_flip(array)

array Required. Specifies an array of key/value pairs to be flipped
Return Value: Returns the flipped array on success. NULL on failure

Example: Flip all keys with their associated values in an array.

<?php 
	$a1 = array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow"); 
	$result = array_flip($a1); 
	print_r($result);
	// Output: Array ( [red] => a [green] => b [blue] => c [yellow] => d )
?>

unset()

The unset() function is used to remove element from the array.
The unset() function accepts a variable name as parameter and destroy or unset that variable.

Syntax:

unset($var,...)

Example:

<?php 
	$xyz = array("CO","ME","CE"); 
	print_r($xyz); 
	unset($xyz); 
	print_r($xyz); 
?>

array_values()

The array_values() function returns an array containing all the values of an array.
Return all the values of an array (not the keys)
The returned array will have numeric keys, starting at 0 and increase by 1.

Syntax:

array_values(array)

Example:

<?php 
	$a = array("Name"=>"Peter","Age"=>"41","Country"=>"USA"); 
	print_r(array_values($a));
	// Output : Array ( [0] => Peter [1] => 41 [2] => USA )
?>

array_slice()

The array_slice() function returns selected parts of an array.
If the array have string keys, the returned array will always preserve the keys

Syntax:

array_slice(array, start, length, preserve)

Example: start the slice from the third array element, and return the rest of the elements in the array.

<?php 
	$a=array("red","green","blue","yellow","brown"); 
	print_r(array_slice($a,2));  
	// Output: Array ( [0] => blue [1] => yellow [2] => brown )
?>

array_merge()

The array_merge() function merges one or more arrays into one array.
You can assign one array to the function, or as many as you like.
If two or more array elements have the same key, the last one overrides the others.
If you assign only one array to the array_merge() function, and the keys are integers, the function returns a new array with integer keys starting at 0 and increases by 1 for each value (See example below).
The difference between this function and thearray_merge_recursive()function is when two or more array elements have the same key. Instead of override the keys, the array_merge_recursive() function makes the value as an array.

Syntax:

array_merge(array1, array2, array3, ...)

Example 1:

<?php 
	$a1 = array("red","green"); 
	$a2=array("blue","yellow"); 
	print_r(array_merge($a1,$a2));
	// Output : Array ( [0] => red [1] => green [2] => blue [3] => yellow )
?>

Example 2:

<?php 
	$a1 = array("a"=>"red","b"=>"green");
	$a2=array("c"=>"blue","b"=>"yellow");
	print_r(array_merge($a1,$a2));
	// Output: Array ( [a] => red [b] => yellow [c] => blue )
?>

Sorting Arrays Functions

The elements in an array can be sorted in alphabetical or numerical order, descending or ascending.

sort() : sort arrays in ascending order

rsort() : sort arrays in descending order

asort() : sort associative arrays in ascending order, according to the value

ksort() : sort associative arrays in ascending order, according to the key

arsort() : sort associative arrays in descending order, according to the value

krsort() : sort associative arrays in descending order, according to the key

Example: Sorts the elements of the $cars array in ascending alphabetical order:

<?php 
	$cars = array("Volvo", "BMW", "Toyota"); 
	sort($cars); 
?>

Example: Sorts the elements of the $numbers array in ascending numerical order:

<?php 
	$numbers = array(4, 6, 2, 22, 11); 
	sort($numbers); 
?>

Array Iterator Functions

next() : move to next element in array

prev() : move to previous element in array

end() : move to last element in array

each() : return the key and value of current element in array

pos() : returns the value of the current element in an array.

current() : return current point element

key() : return the key of current element in array

reset() : move to first element in array

Example:

<?php 
	$people = array("Sumit", "Amita", "Shiv", "Mitali"); 
	echo current($people) . "<br>"; 
	echo next($people). "<br>"; 
	echo prev($people). "<br>"; 
	echo pos($people) . "<br>"; 
	echo end($people). "<br>"; 
	echo reset($people). "<br>"; 
	echo "The key from the current position is: " . key($people)."<br>"; 
	print_r (each($people)); 
?>

Output:

Sumit 
Amita 
Sumit 
Sumit 
Mitali 
Sumit 
The key from the current position is: 0 
Array (
 [1] => Sumit 
 [value] => Sumit 
 [0] => 0 
 [key] => 0 
)

Menu

Extract()

list()

Compact()

implode()

explode()

array_flip()

unset()

array_values()

array_slice()

array_merge()

Sorting Arrays Functions

Array Iterator Functions

Introduction to Algorithm

Recursion Algorithm