Answer 1, authority 100%

Sorting by custom function: usort () .

usort ($ array, function ($ a, $ b) {
  return ($ a ['price'] - $ b ['price']);
});

Answer 2, authority 24%

$ data = array
(
  array ('name' = & gt; 'title 1', 'price' = & gt; 200),
  array ('name' = & gt; 'title 2', 'price' = & gt; 100)
);
usort
(
  $ data,
  create_function
  (
    '$ a, $ b',
    'return - ($ a ["price"] - $ b ["price"]);' # return the desired value
  )
);

1) do not forget that price fields must be int, not strings (otherwise, an explicit conversion is needed)

2) if you need reverse sort order:

return $ a ["price"] - $ b ["price"];

Answer 3, authority 18%

You can convert it to an array like this:

Answer 4, authority 18%

Found on the Internet:

function cmp ($ a, $ b) {
 return strnatcmp ($ a ["product_order"], $ b ["product_order"]);
}
usort ($ parts, "cmp");

Answer 5, authority 6%

the uasort function is designed to be sorted using a custom function, but preserving the array keys (unlike usort).

Answer 6

I suffered for a long time with a similar problem, here is my solution:

principle:

• build another array “2” where the key of the new array = the key of the old one, and the value itself = the value by which we want to sort;
• sorting the new array “2” SAVING KEYS (asort, arsort);
• well, and then we build another array “3” based on array “2” – we go through array “2” and along the way insert into array “3” “a subarray” of array “1” by the key of array “2”;
• array “3” is our sorted one.

for ($ i = 0; $ i & lt; count ($ array); $ i ++) {
  $ sortkey [$ i] = $ array [$ i] ['price'];
}
asort ($ sortkey); // ascending, arsort ($ sortkey) - descending
foreach ($ sortkey as $ key = & gt; $ key) {
  $ sorted [] = $ array [$ key];
}