PHP排序多维数组键升序

Question

I have this array:

Array => (
    [0] => Array(
        [a] => hello,
        [b] => world
    ),
    [1] => Array(
        [a] => bye,
        [b] => planet
    ),
    .....
)

And I need a function to sort it into this:

Array => (
    [0] => Array(
        [a] => bye,
        [b] => planet
    ),
    [1] => Array(
        [a] => hello,
        [b] => world
    ),
    .....
)

Been hours trying and I am going mad, please help me.

Thanks!!

Answer 1

If you mean to sort the array based on the contents of all the strings in the array, you're going to have to apply some logic to the sort. Using usort allows us to pass in an arbitrary function to perform the comparison.

usort($my_array, function ($a, $b) {
    return strcasecmp(implode($a), implode($b));
});

This way, it'll compare two arrays like so:

array 1 = [ 'foo', 'bar' ]
array 2 = [ 'baz', 'quux' ]
array 1 is converted to "foobar"
array 2 converted to "bazquux"
compare strings "foobar" to "bazquux"
-> "bazquux" comes first alphabetically, so strcasecmp() return positive integer
-> usort receives the positive integer which informs its sorting algorithm

Answer 2

You could use array_reverse(). PHP has many built in array functions. http://php.net/manual/en/ref.array.php

$test = Array (
    0 => Array(
        'a' => 'hello',
        'b' => 'world'
),
    1 => Array(
        'a' => 'bye',
        'b' => 'planet'
    ),
);
$reverse = array_reverse($test);
print_r($reverse);
Array ( 
    [0] => Array ( 
        [a] => bye 
        [b] => planet 
    ) 
    [1] => Array ( 
       [a] => hello 
       [b] => world 
    )
 )