Detailed explanation of how PHP inserts elements before the Key specified in an associative array

This article mainly introduces the method of PHP to insert elements before the Key specified in the associative array, involving PHP's array traversal, judgment, acquisition, insertion and other related operation skills. Friends in need can refer to it

The details are as follows:

PHP associative arrays can insert new elements in three ways:

1. $array[$insert_key] = $insert_value;
2. $array = array_merge($array, $insert_array);
3. $array = $array $insert_array;

But if you want to specify What about inserting elements before the key? The following code inserts $data into the associative array $array before the key named $key:

function wpjam_array_push($array, $data=null, $key=false){
  $data  = (array)$data;
  $offset  = ($key===false)?false:array_search($key, array_keys($array));
  $offset  = ($offset)?$offset:false;
  if($offset){
    return array_merge(
      array_slice($array, 0, $offset),
      $data,
      array_slice($array, $offset)
    );
  }else{  // 没指定 $key 或者找不到，就直接加到末尾
    return array_merge($array, $data);
  }
}

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