Arrays are sets of data which can be defined in a PHP Script. Arrays can contain other arrays inside of them without any restriction (hence building multidimensional arrays). Arrays can be referred to as tables or hashes.

Syntax:

Arrays can be created in two ways. The first involves using the function array. The second involves using square brackets.

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The array function method :

In the array function method, you create a array in the scheme of:
$foo = bar()
For example, to set the array up to make the keys sequential numbers (Example: "0, 1, 2, 3"), you use:
$foobar = array($foo, $bar);
This would produce the array like this:
$foobar[0] = $foo
$foobar[1] = $bar
It is also possible to define the key value:
$foobar = array('foo' => $foo, 'bar' => $bar);
This would set the array like this:
$foobar['foo'] = $foo
$foobar['bar'] = $bar

The square brackets method :

The square brackets method allows you to set up by directly setting the values.
For example,to make $foobar[1] = $foo, all you need to do is:
$foobar[1] = $foo;
The same applies for setting the key value:
$foobar['foo'] = $foo;

    <?php
    $array =
    array("name"=>"priya","occupation"=>"IT professional","qualification"=>"BSC-IT","religion"=>"Humanity");
    $array2 = array("priya","IT professional","BSC-IT","Humanity");
    $array3 = array("name"=>"priya","IT professional","colour"=>"BSC-IT","Humanity");
    print_r($array);
    print_r($array2);
    print_r($array3);
    ?>
     

PHP Output:

    Array ( 
    [name] =>Priya
    [occupation] => IT professional 
    [qualification] => BSC-IT 
    [religion] => Humanity
     )
     Array (
    [0] =>priya
    [1] => IT professional 
    [2] => BSC-IT 
    [3] => Humanity
     ) 
    Array ( 
    [name] =>Priya
     [0] => IT professional
     [colour] => BSC-IT 
    [1] => Humanity 
    )

     

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Multidimensional Arrays :

Elements in an array can also be an array, allowing for multidimensional arrays.

https://www.w3schools.com/php/php_arrays_multidimensional.asp

Array Functions :

There exist dozens of array manipulation functions. Before implementing your own, make sure it doesn't already exist as a PHP function in Array functions (PHP manual entry).

Array traversal :

In various circumstances, you will need to visit every array element and perform a task upon it.
The simplest and the most widely used method for this is the foreach operator which loops through the whole array and works individually with each key/item couple. If a more complex way of traversing the array is needed, the following functions operate using the internal array pointer:
reset - sets the internal pointer to the first element and returns the first element
prev - sets the internal pointer to the previous element and returns it
current - returns the current element; does not change the internal pointer
next - sets the internal pointer to the next element and returns it
each - returns the current element; then sets the internal pointer to the next element
end - sets the internal pointer to the last element and returns the last element

    <?php
    // using an array's iterator to print its values in reverse order
    $my_array = array('a', 'b', 'c');
    end($my_array); 
    while($i = current($my_array)){
    echo $i."\n"; 
    prev($my_array);
    } 
    ?>

     

In various circumstances, you will need to visit every array element and perform a task upon it.
Another possibility is defining a function and applying it to each array element via one of the following functions:
array_walk - applies a function to each array element.
array_walk_recursive - same, but if the element is itself an array, it will traverse that array too.