php - sort an associative array -

How can I sort this array by SAP ASC?

  [xml] = & gt; Array ([sales] = & gt; Array ([0] => Array ([RF]] => 316205 [Line] => 3 [partno] => MC41SS [cust] => [ Date] = & gt; 28 / 6/10 [value] => [remainder] => [SASP] => CDA [stadici] => CDA built / freestanding M / wave grill / convection Oven [sdelinfo] = & gt;) [1] = & gt; Array ([RF]] => 316657 [line] => 1 [partno] => SRS 45 E 48 GB [CAT] => [ Date] = & gt; 7 / 7/10 [value] = & gt; [remaining] => [Ssup] => Bosch [stdesc] => Bosch S / L4 Progress Express Wash 49 dB Dishwasher silver [sdelinfo] = & gt;) [2] => Array ([ref] => 316791 [line] = & gt; 1 [partno] => T44T90N0 [cust] => [date] => 9 / 7/10 [value] => [remainder] = & gt; [SAST] => NEF [Stdesc] = & gt; Nef 90cm Front Control Point and Twist Hob St.Saint [SDLIFO] = & gt;)  

  function cmp ($ a, $ b) {if ($ A ['ssup'] == $ b ['ssup']) {return 0; } Return ($ a ['ssup'] & gt; $ b ['ssup'])? -1 1; } Usort ($ array, "cmp");