合并两个数组，用第二个数组覆盖第一个数组

Question

I would like to merge two arrays containing a list of files plus their revision in brackets.

For example:

Fist array:

0 => A[1], 1 => B[2], 2 => C[2], 3 => D[2]

Second one,

0 => B[3], 1 => C[4], 2 => E[4], 3 => F[2], 4 => G[2]

Like I said, I would be able to merge both arrays, but overwriting the first one by the data present in the second one.

I used this regex to only grab filenames (removing the revision number). I don't know if I am correct on this point):

/\[[^\)]+\]/

The result I am looking for would be this,

0 => A[1], 1 => B[3], 2 => C[4], 3 => D[2], 4 => E[4], 5 => F[2], 6 => G[2]

Also, I was about to forget, the whole thing is in PHP.

Answer 1

something like:

function helper() {
  $result = array();

  foreach (func_get_args() as $fileList) {
    foreach ($fileList as $fileName) {
      list($file, $revision) = explode('[', $fileName, 2);
      $revision = trim($revision, ']');
      $result[$file] = !isset($result[$file]) ? $revision : max($result[$file], $revision);
    }
  }

  foreach ($result as $file => $revision) {
    $result[$file] = sprintf('%s[%s]', $file, $revision);
  }

  return array_values($result);
}

$a = array('A[1]', 'B[2]', 'C[2]', 'D[2]');
$b = array('B[3]', 'C[4]', 'E[4]', 'F[2]', 'G[2]');

print_r(helper($a, $b));

demo: http://codepad.org/wUMMjGXC

Answer 2

One way would be to map both arrays to

filename => filename[revision]

such that

Array
(
    [0] => A[1]
    [1] => B[2]
    [2] => C[2]
    [3] => D[2]
)

becomes

Array
(
    [A] => A[1]
    [B] => B[2]
    [C] => C[2]
    [D] => D[2]
)

and then use array_merge (which overrides entries with the same key).

Something like:

function map($array) {
    $filenames = array_map(function($value) {
        return strstr($value, '[', false);
    }, $array);
    return array_combine($filenames, $array);
}

$result = array_merge(map($array1), map($array2));

If you want to have numeric indexes, you can call array_values on the result. The code above requires PHP 5.3 but it should be easy to make it compatible with earlier versions. The other caveat is that it would only work if filenames are unique in the array.

DEMO (PHP 5.2 version)

Reference: array_map , strstr , array_combine , array_merge

Answer 3

You could use the union operator :

$newArray = $arr1 + $arr2;

You are right, array_merge would only work if your keys were strings. With numeric keys, the second array will just be appended to the first, without overwriting duplicate keys.