PHP : Array Functions Tutorial – Part 2

This is continuation to Array Functions Tutorial.

Previous Articles can be read from here

PHP : Array Functions Tutorial – Part I
What is an Array? Functions of Array- Array Tutorials

Function : Check if array index is set and whether it has a value.
Function: Get Random Element from Array

Array Function – Part II


array_flip()

This function flips between the keys and their values i.e. that keys becomes values and values becomes keys.

Syntax:

 array_flip($array) 

Example:


$array = ("a"=>"apple", "b"=>"bat", "c"="cat");

$new_array = array_flip($array);

print_r($new_array);

Output:


Array(

[apple]=>a

[bat]=>b

[cat]=>c

)

Example:


$array = ("a"=>"apple", "a"=>"ant", "c"="cat");

Output:


Array(

[ant]=>a

[cat]=>c

)

array_key_exists()

This function check if the key/index in the array exists. It returns true if the key/index is found else false. This function does not works on array objects(from php version 5.3.0)

Syntax:

array_key_exists($key,$array);

Example:

$array = ("a"=>"apple", "b"=>"bat", "c"=>"cat");
if(array_key_exists("a",$array))
{
echo "key found";  // This is output
}
else
{
echo "key not found";
}

array_fill_keys()

This function fills/populates an array with specific value to the keys assigned.

Syntax:

array_fill_keys($array_keys,$string_value);

Example:


$keys = array("a","e","i","o","u");

$string = "vowel";

$new_array = array_fill_keys($keys,$string);

Output:


Array (

[a]=>vowel,

[e]=>vowel,

[i]=>vowel,

[o]=>vowel,

[u]=>vowel

)

array_fill()

This function fills/populates an array with values based on the range of keys provided.

Syntax:

 array_fill($start_index,$limit,$value); 

If limit is less than 1 then E_WARNING is thrown

Example:


$array_1 = array_fill("3","4","php-array-tutorials");

$array_2 = array_fill("-3","4","php-array-tutorials-part-2");

print_r($array_1);

print_r($array_2);

Output:


Array(

[3]=>php-array-tutorials

[4]=>php-array-tutorials

[5]=>php-array-tutorials

[6]=>php-array-tutorials

)

Array(

[-3]=>php-array-tutorials-part-2

[0]=>php-array-tutorials-part-2

[1]=>php-array-tutorials-part-2

[2]=>php-array-tutorials-part-2

)

array_map()

This function applies a callback funtion to all the elements of the array

Syntax:

array_map($function, $array);

Example:


$array = array("apple","bat","cat");

$new_array = array_map("strtoupper",$array);

print_r($new_array);

Output:


Array(

[0]=>APPLE

[1]=>BAT

[2]=>CAT

)

array_unique()

This function removes duplicate entries from an array. Keys are preserved in the return value. If two value matches, the first occurance is used.

Syntax:

array_unique($array);

Example:


$array = array("fruit1"=>"apple","fruit2"=>"apple","fruit3"=>"mango","fruit4"=>"orange");

$new_array = array_unique($array);

Output:


Array(

[fruit1]=>apple,

[fruit3]=>mango,

[fruit4]=>orange

)

count()

This function counts the number of elements in an array or an object.

Syntax:

count($array)

Example:


$array = array("fruit1"=>"apple","fruit2"=>"apple","fruit3"=>"mango","fruit4"=>"orange");

echo count($array);

Output:


4

size_of()

This function is an alias of count(). You can refer to count() for more info.

Suggestion, Comments, Improvements and Questions are always welcome.

Reference:
PHP : Array Functions Tutorial – Part I
What is an Array? Functions of Array- Array Tutorials

Function : Check if array index is set and whether it has a value.
Function: Get Random Element from Array
PHP.net

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