Switching two keys of an array

Question

I feel like I am so close to successfully switching Jim and Jill in this associative array. I ALSO would like it to be repeatable, so if 'Joe' is added to the end, it will also swap 'Jim' and 'Joe.' Any pointers?

 <?php
 function jim_is_jill($their_name) {

    $first = key($their_name);

    foreach ($their_name as $key => $value) {
        $lastmaybe = $key;
    }   
        $lastmaybe = $these;              // Lastmaybe is Jill
        $these     = $first;

        return $their_name;
 }  

 $their_name = array(
 //       Key   =>  Value
         'Jim'   => 'dad', 
         'Josh'  => 'son', 
         'Jamie' => 'mom', 
         'Jane'  => 'daughter', 
         'Jill'  => 'daughter'
         );

 print_r(jim_is_jill($their_name));
 ?>

CURRENT OUTPUT:

Array
(
    [Jim] => dad
    [Josh] => son
    [Jamie] => mom
    [Jane] => daughter
    [Jill] => daughter
)

DESIRED OUTPUT:

Array
(
    [Jill] => dad
    [Josh] => son
    [Jamie] => mom
    [Jane] => daughter
    [Jim] => daughter
)

Answer 1

First thing, in my experience, it's not wise to rely on the order of an array, if it is not indexed by numbers. There are no tools (correct me if I'm wrong) to switch positions of keys or change keys themselves. It would have to be ugly hack. The only way to rename a key is to remove it and put it back correctly. But that disturbs the order of an array. You'll really have to rebuild the array from scratch, that's an easiest way, as suggested by Yanick, if you really want to do what you want to do. But there's more neat solution. You can make an array with numbered indexes, which you-shall-not-touch. That way, it will stay order. Then put simple small array in each value:

array('name'=> 'Jill, 'relationship'=>'daughter);

That way, you have full control of the order of indexes (thanks to numbered indexes) and you will only have to swap values, which is dead easy.

Or, you can omit those words and give it just numbered indexes everywhere. That way you'll write less but you will have to remember which is which:

array('jill', 'daughter');

is effectively same as:

array(0 => 'Jill', 1 => 'daughter');

So here's the code..

<?php

function swap_first_and_last($their_name) {

    //get first and last keys
    reset($their_name); // resets the array pointer to beginning
    $k_first=key($their_name); // first key
    end($their_name);
    $k_last=key($their_name); // last key



    // swap first and last:
    $swap = $their_name[$k_first]['name'];
    $their_name[$k_first]['name']=$their_name[$k_last]['name'];
    $their_name[$k_last]['name']=$swap;

    // note: you can use [0] and [1], if you modify your array that way

    return $their_name;
}

// modified array
 $their_name = array(
 // note, you can omit those 0 => , 1 => ,2,... keys
                 0 => array('name' => 'Jim', 'relationship' => 'dad'),
                 1 => array('name' => 'Josh', 'relationship' => 'son'),
                 2 => array('name' => 'Jamie', 'relationship' => 'mom'),
                 3 => array('name' => 'Jane', 'relationship' => 'daughter'),
                 4 => array('name' => 'Jill', 'relationship' => 'daughter')
                 );



var_dump(swap_first_and_last($their_name));

And the result is:

array (size=5)
    0 => 
        array (size=2)
            'name' => string 'Jill' (length=4)
            'relationship' => string 'dad' (length=3)
    1 => 
        array (size=2)
            'name' => string 'Josh' (length=4)
            'relationship' => string 'son' (length=3)
    2 => 
        array (size=2)
            'name' => string 'Jamie' (length=5)
            'relationship' => string 'mom' (length=3)
    3 => 
        array (size=2)
            'name' => string 'Jane' (length=4)
            'relationship' => string 'daughter' (length=8)
    4 => 
        array (size=2)
            'name' => string 'Jim' (length=3)
            'relationship' => string 'daughter' (length=8)

Answer 2

Considering the array

$their_name = array(
 //   Key   =>  Value
    'Jim'   => 'dad', 
    'Josh'  => 'son', 
    'Jamie' => 'mom', 
    'Jane'  => 'daughter', 
    'Jill'  => 'daughter'
);

This function will produce :

function array_swap_values($array, $key1, $key2) {
    $temp = $array[$key1];
    $array[$key1] = $array[$key2];
    $array[$key2] = $temp;
    return $array;
}

$their_name = array_swap_values($their_name, 'Jim', 'Jill');
// -> array(
//      'Jim'   => 'daughter', 
//      'Josh'  => 'son', 
//      'Jamie' => 'mom', 
//      'Jane'  => 'daughter', 
//      'Jill'  => 'dad'
// );

Or this function will produce

function array_swap_keys($array, $key1, $key2) {
    $ret = array();
    foreach ($array as $key => $value) {
        if ($key === $key1) {
            $ret[$key2] = $array[$key2];
        } else if ($key === $key2) {
            $ret[$key1] = $array[$key1];
        } else {
            $ret[$key] = $value;
        }
    }
    return $ret;
}

$their_name = array_swap_keys($their_name, 'Jim', 'Jill');
// -> array(
//      'Jill'  => 'daughter', 
//      'Josh'  => 'son', 
//      'Jamie' => 'mom', 
//      'Jane'  => 'daughter', 
//      'Jim'   => 'dad'
// );

** Update **

After your last edit, I modified the last function to return what is expected. It is pretty close to the first function, but it preserve the key ordering :

function array_swap_key_value($array, $key1, $key2) {
    $ret = array();
    foreach ($array as $key => $value) {
        if ($key === $key1) {
            $ret[$key2] = $array[$key1];
        } else if ($key === $key2) {
            $ret[$key1] = $array[$key2];
        } else {
            $ret[$key] = $value;
        }
    }
    return $ret;
}

$their_name = array_swap_key_value($their_name, 'Jim', 'Jill');
// -> array(
//      'Jill'  => 'dad', 
//      'Josh'  => 'son', 
//      'Jamie' => 'mom', 
//      'Jane'  => 'daughter', 
//      'Jim'   => 'daughter'
// );