How to get numeric index of associative array in PHP?

In PHP we can associate name/label with each array elements using => symbol. This is very helpful as it is easy to remember the element because each element is represented by the label rather than the index value.
Using array_keys() function: The array_keys() function is an inbuilt function in PHP which is used to return either all the keys of an array or the subset of the keys.

Syntax:

array array_keys( $input_array, $search_value, $strict )

Program 1: Program to get numeric index of associative array using array_keys() function.

<?php

// Program to print index of an associative array

// Declare an associative array
$assoc_array=array("Geeks"=>10, "for"=>15, "geeks"=>20);

// Print index with corresponding key
// using array_keys() function
print_r(array_keys($assoc_array));

?>

Example 2: Below program uses index to access the values in associative array.

<?php

// Program to print values using index
// of associative array

// Declare an associative array
$assoc_array = array(
    "Geeks" => 30,
    "for" => 20,
    "geeks" => 10
);

// Using array_keys() function
$key = array_keys($assoc_array);

// Calculate size of array
$size = sizeof($key);

// Using loop to access values
for( $i = 0; $i < $size; $i++) {
    echo "${assoc_array[$key[$i]]}\n";
}

?>