sorting an associative array by boolean field

$list is populated thusly: -

$list[$i++] = array(
    "date" => $date,
    "desc" => $desc,
    "开发者_StackOverflowpriority" => $priority
);

$priority is set to TRUE if it matches some criteria.

I'd like the $list to be sorted with rows that have a priority TRUE at the top.

The list is already sorted by date which I wish to preserve.

In PHP>=5.3

usort ($array, function ($left, $right) {
    return $left['priority'] - $right['priority'];
});

Or in earlier version

function cmp($left, $right) {
    return $left['priority'] - $right['priority'];
}
usort($array, 'cmp');

Or use create_function() (also for version < 5.3)

usort ($array, create_function('$left,$right', 'return $left[\'priority\'] - $right[\'priority\'];'));

This works, because (int) true === 1 and (int) false === 0

true - true == 0
true - false == 1
false - true == -1
false - false == 0

Use usort and supply your own sort function describing whether true is greater then false or the other way around.

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

usort($array, "cmp");

if you want to change the stability of the sort, where elements are sorted if they have the same priority value, then just modify the cmp function.

use this function

function sort2d ($array, $index, $order='asc', $natsort=FALSE, $case_sensitive=FALSE)  
    { 
        if(is_array($array) && count($array)>0)  
        { 
           foreach(array_keys($array) as $key)  
               $temp[$key]=$array[$key][$index]; 
               if(!$natsort)  
                   ($order=='asc')? asort($temp) : arsort($temp); 
              else  
              { 
                 ($case_sensitive)? natsort($temp) : natcasesort($temp); 
                 if($order!='asc')  
                     $temp=array_reverse($temp,TRUE); 
           } 
           foreach(array_keys($temp) as $key)  
               (is_numeric($key))? $sorted[]=$array[$key] : $sorted[$key]=$array[$key]; 
           return $sorted; 
      } 
      return $array; 
    }

and call

sort2d ($list, $priority);

Reference