Array Functions in PHP: PART 7

Introduction

In this article I describe the PHP array functions array_key_exists, array_keys and array_map. To learn some other math functions, go to:

1. Array Functions in PHP: PART 1
    
2. Array Functions in PHP: PART 2
    
3. Array Functions in PHP: PART 3
    
4. Array Functions in PHP: PART 4
    
5. Array Functions in PHP: PART 5
    
6. Array Functions in PHP: PART 6
    

PHP array_key_exists Function

The PHP array_key_exists function deterimes whether the specified key or index exists in the given array or not and returns true if it exists otherwise false.

Syntax

array_key_exists(key, array)

Parameters

The parameters of the array_key_exists function are:

Parameter	Description
key	It specifies key.
array	It  specifies an array.

Example

An example of the array_key_exists function is:

<?php
echo "<pre>";
$val = array("a" => "Apple", "b" => "Mango", "c" => "Orange", "Banana");
if(array_key_exists("a",$val))
{
echo "Key exists!";
}
else
{
echo "key does not exists!";
}
?>

Output


PHP array_keys Function

The PHP array_keys function accepts an array and returns a new array that contains only its keys.

Syntax

array_keys(array,values)

Parameters

The parameters of the array_keys function are:

Parameter	Description
array	It specifies an array.
values	It  specifies values, then only keys with this values are returned.

Example

An example of the array_keys function is:

<?php
echo "<pre>";
$val = array("a" => "Apple", "b" => "Mango", "c" => "Orange", "Banana");
echo "Without Value Parameter: ";
print_r(array_keys($val));
echo "<pre>";
echo "With Value Parameter: ";
print_r (array_keys($val,"Mango"));
?>

Output



PHP array_map function

The array_map function sends each value of an array to the user-defined function and returns an array containing all the elements of arr1 after applying the user-defined function to each one.

Syntax

array_map( userDefinedFunction, array1, array2,........................)

Parameters

The parameters of the array_map function are:

Parameter	Description
userDefinedFunction	It specifies name of user defined function.
array1	It specifies an array.
array2	It  specifies an array.

Example

An example of the array_map function is:

<?php
function myfunction($array1)
{
if ($array1==="Mango")
{
return "orange";
}
return $array1;
}
$array1 = array(1 => "Apple",  2=> "Mango", 3 => "Orange", "Banana");
echo "<pre>";
$result = array_map("myfunction",$array1);
print_r($result);
?>

Output