Question

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Sorting a multidimensional array?

I have an a multi dimesional associative array:

[book]=>{
            [names]=>{
                        [name]=>'thing1',
                        [age]=>'23',
                        [nOrder]=>'1'
                     },
                     {
                        [name]=>'thing2',
                        [age]=>'24',
                        [nOrder]=>'3'
                     },
                     {
                        [name]=>'thing3',
                        [age]=>'25',
                        [nOrder]=>'2'
                     }
        }

Hope that example looks ok, basically I need to re-order the positions of the rows within the “names” value to be in order form 1 to 3 by whatever is in the “nOrder” value.

Answer 1

function cmp( $a, $b ) {
    return $a['nOrder'] > $b['nOrder'] ? 1 : -1;
}

usort( $book['names'], 'cmp' );

from usort manual page:

This function will sort an array by its values using a user-supplied comparison function. If the array you wish to sort needs to be sorted by some non-trivial criteria, you should use this function.

We pass cmp as the comparison function to usort() and it will sort elements of $book['names'] array using that comparison function.