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Array Functions in PHP

In PHP, Programming by Baqir Ali

PHP provides some built-in functions to make array operations easy for programmers such as sorting, searching, or other array operations.

Array Sorting Functions In PHP

Function What It Does
array_multisort() Sorts multiple or multidimensional arrays
arsort() Reverse sorts associative arrays alphabetically by value. The index association remains intact.
asort() Sorts  associative  arrays  alphabetically  by  value.   The       index association remains intact.
krsort() Reverse sorts associative arrays alphabetically by key. The index association remains intact.
ksort() Sorts   associative   arrays   alphabetically   by   key.   The        index association remains intact.
natcasesort() Sorts an array using a case–‐insensitive “natural order” algorithm
natsort() Sorts an array using a “natural order” algorithm
rsort() Sorts an array in reverse order
shuffle() Shuffles an array
sort() Sorts an array
uasort() Sorts  an  array  with  a  user–‐defined   comparison       function   and maintains index association
uksort() Sorts an array by keys using a user–‐defined comparison function
usort() Sorts an array by values using a user–‐defined comparison function

Example 1: Sorting an array in ascending order


			for ($i=0; $i <count($list) ; $i++) { 
				echo $list[$i]." ";


23 34 34 45 54 54 56 65 67 76 87

Array Sort Flags in PHP

Flag What It Does
SORT_LOCALE_STRING Compares  items  as  strings,  based  on  the          current locale
SORT_NUMERIC Compares items numerically
SORT_REGULAR Compares items normally (does not change types)
SORT_STRING Compares items as strings

Array Manipulation Functions

Function Explanation
array_count_values() Returns an array consisting of the values of an array and the number of times each value occurs in an array $hash_count = array_count_values( array(“a”,”b”, “a”,”a”)); // Creates an associative array with “a” and “b” as the two keys and the number of times each occurs in the array (the associated value)
array_fill(5, 6,“php”) Starting from 5 index, fill 6 values, all values “php”
array_key_exists() Checks to see if a specified key exists in an array.
array_keys() Returns all the keys of an associative array as an array. $array_of_keys = array_keys(“apples”, “pears”, “peaches”, “plums”); //Returns0,1,2,3 $array_of_keys = array_keys(“Title”=>”King”, “Name”=>”Barbar”); //Returns “Title”, “Name”
array_pad() Pads an array to the specified length with a value
array_reverse() Returns an array with the elements in reverse order.
array_values() returns an array with all the values of the original array $animals=array(“tiger”, “lion”, “camel”,”elephant”); $array_of_values=array_values($animals); //Returns:”tiger”,”lion”,”camel”,”elephant”
array_walk() Applies a user function to every element of an array.
count() Returns the number of elements in an array.
each() returns the current key–value pair in an array, and moves to the next element, making that the current element. The returned value is an array of two alternating values to represent each key and its corresponding value. To access the array elements, you can use either 0 and 1 to represent each key and value, or the keywords key and value to do the same thing. Used with a looping construct, each element of the array can be accessed until the array has reached its end. The reset() function sets the internal array pointer back to the beginning of the array if you want to access the array elements again.   $colors=array(‘red’,’green’, ‘blue’,’yellow’); while($array = each($colors)) { // echo $array[0].” => ” . $array[1]. “<br />”; echo $array[‘key’].” => ” . $array[‘value’]. “<br />”; }
explode() Splits up a string by a specified delimiter and creates an array of strings $fruit = explode(” “, “apples pears peaches plums”); $fruit = explode(“|”, “apples|pears|peaches|plums”,3);//creates a 3 element array
implode() Creates a string by gluing together array elements by a specific separator $stats_array = array(‘name’, ‘ssn’, ‘phone’); $stats_string = implode(“,”, $stats_array);
in_array() Checks if a value exists in an array
is_array() Takes one parameter and returns true or false depending on whether the parameter passed is an array.
join() Alias for implode()
range(start,end,step) range(1, 5) // returns 1, 2, 3, 4, 5 range(1, 10, 2) //returns 1, 3, 5, 7, 9 range(15, 0, -5) //15, 10, 5, 0 range(-2, -8) //-2, -3, -4, -5, -6, -7, -8 range(‘a’,’c’) //a, b, c
rsort() Reverse sorts an array alphabetically. Elements will be assigned to new index numbers.
shuffle() Randomly sorts the array. For the order to be sorted differently each time, the random number generator needs to be seeded with rsand(). $numbers = ( 1, 2, 3, 4, 5, 6, 7, 8, 9, 10); shuffle($numbers);
sizeof() Returns the size of the array, same as count()
sort() Sorts an array alphabetically. Elements will be assigned to new index numbers.
split() Splits up a string into an array by a regular expression
list() extracts elements from a numeric array (with index starting at 0) and assigns them to individual variables. Its arguments are a comma-separated list of variable names   $swatch = array(‘blue’, ‘#33A1C9’, ‘peacock’); list($color, $code, $name) = $swatch; // Create variables from array list($color, $code) = $swatch; // Ignore ‘peacock’ list($color, , $name)=$swatch; // Skip ‘#33A1C9’
extract() creates variables from any associative array. The variables are named after the keys, and the values assigned to them are the same as the correspnding values in the associative array.   $television  =  array(“model”=>”Pan  PX-44BBCCSTV”,”type”=>”plasma”, “color”=>”charcoal bezel”, “size”=>”42 in. widescreen”); extract($television);// Create variables from keys print ” Model number after <em>extract(): $model</em><p>”; print “Values of variables created by <em>extract():<br />”; print “$model, $type, $color, $size</em><br />”;
array_rand() The array_rand() function lets you select one or more random entries from an array. It takes an array as its argument and by default returns one random key or index value. If a second optional numeric argument is given, you can specify how many random keys to pick from the array, and an array of that number of random keys will be returned

$random= array_rand($colors);
// Returns a random color
$random= array_rand($colors, 2); // Returns two random colors print $colors[$random[0]];
print $colors[$random[1]];

Example 2: Using explode function in PHP


$list="A brown quick, fox jumps, over the lazy dog";
		$newlist=explode(' ', $list);
		for ($i=0; $i <count($newlist) ; $i++) { 
			echo $newlist[$i]. "<br>";



Removing an Array and its Elements in PHP

Function What It Does
array_pop() Removes and returns the last element of an array
array_shift() Removes and returns the first element of an array
array_splice() Removes and/or replaces elements in an array
array_unique() Removes duplicates from an array
unset() Removes an entire array

Adding Elements to an Array in PHP

Function What It Does
array_push() Pushes a new element(s) onto the end of the array
array_splice() Removes or adds elements
array_unshift() Adds a new element(s) to the beginning of the array

Combining and Merging Arrays in PHP

Function What It Does
array_combine() returns an array made up of keys and values. The keys of the new array are made up of the values from the first array and the values associated with the new keys are made up of the values from the second array (PHP 5). The function returns FALSE if there are an unequal number of values in either of the arrays used as arguments.
array_merge() joins two or more arrays together to return a single array. The   values   of     one  array     are appended     to      the end  of     the previous array.

Array Operators in PHP

Operator Function Meaning
$a + $b Union Union Of $a And $b
$a == $b Equality TRUE If  $a  And $b  Have the same key–value pairs
$a === $b Identity TRUE If  $a  And $b  Have the same key–value pairs in the same order and of the same types
$a != $b Inequality TRUE If $a Is not equal to $b
$a <> $b Inequality TRUE If $a Is not equal to $b
$a !== $b Nonidentity TRUE if $a is not identical to $b

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