对具有某些已知值的数组进行优先排序，php

Question

I want to sort an array based on a sub array value, that part is fairly simple, but there is an additional requirement.

I also have a known set of values, in which case I want to sort by those instead

In this case the values I am sorting by are IP addresses.

For example, if the address is 1.1.1.5, I want that address to be the first value in the list, and if its 1.1.7.3, I want that to be the second value on the list, and so on.

Then once I am out of known addresses, I want the rest to simply be sorted normally.

The starting order of the array is completely random If possible I also want to append something to the front of the known IPs

How I sort it without the prioritization:

uasort($array, function func($a, $b) {
    return strcmp($a[4], $b[4]);
});

Answer 1

I do not think you can change the IP value within the sort so that would need to be done afterwards. How about something like this though for the sort function (you would need to test performance):

$knownIPs = array(
    '1.1.1.5' => 1,
    '1.1.7.3' => 2,
);

$array = array(
    array('f', '0.0.0.0'),
    array('t', '1.1.7.3'),
    array('w', '1.1.1.5'),
    array('r', '1.1.1.6'),
    array('c', '1.1.1.7'),
    array('a', '1.1.1.8'),
    array('i', '1.1.1.9'),
);

uasort($array, function ($a, $b) {
  global $knownIPs;

  $knownIPsKeys = array_keys($knownIPs);
  //if a is a known IP then it has to be before any unknown IP
  if(in_array($a[1],$knownIPsKeys) && !in_array($b[1],$knownIPsKeys)){
    return -1;
  }
  //if b is a known IP then it has to be before any unknown IP
  if(in_array($b[1],$knownIPsKeys) && !in_array($a[1],$knownIPsKeys)){
    return 1;
  }
  //if a and b are both known then check if their order is the same or different
  if(in_array($a[1],$knownIPsKeys) && in_array($b[1],$knownIPsKeys)){
    //if a and b have the same order then compare on the other field as per default
    if($knownIPs[$a[1]]===$knownIPs[$b[1]]){
      return strcmp($a[0], $b[0]);
    }
    //otherwise compare on the order value
    return $knownIPs[$a[1]]<$knownIPs[$b[1]]?-1:1;
  }
  //compare on other field as default
  return strcmp($a[0], $b[0]);
});

print_r($array);

This is a simple script using a global variable to hold the known IPs, there are a number of different ways that $knownIPs can be set up and used depending obviously on the rest of your code but hopefully this gives an idea of how to achieve the sorting.