I'm wondering when, if ever it would be appropriate to use an ArrayObject() instead of an Array()? Here's an example i've been working on.
To me i'm thinking a simple array will work, but i found ArrayObject() in the manual and I'm wondering, if it would be better to use one instead of a simple array.
public function calculateTotal(){
if(count($this->items) > 0){
$n = 0;
foreach($this->items as $item){
if($item->size == 'small'){
$k = $item->price->small;
}
if($item->size == 'large'){
$k = $item->price->large;
}
$n += $k * $item->quantity;
}
}else{
$n = 0;
}
return (int) $n;
}
Now I'm confused as to how i should construct the object.
for instance can i construct it with the short array syntax?
$this->items = []; //empty object
or should i construct is as an Array object
$this->items = new ArrayObject(); //empty object
I'm also confused as to how exactly i should push new items to the array.
i have the following function i'm writing:
Also how should i append arrray objects to this object?
is this good?
public function additem($item){
$add = [
'item_id'=>$this->item_id(),
'name'=>$item['name'],
'size',$item['size'],
'quantity'=>$item['quantity'],
'price'=>[
'large'=>$item['price'],
'small'=>$item['price']
]
]
array_push($this->items,$add);
}
or should i instead use ArrayObject::append() or some other method?
I checked the manual and it says this:
public void ArrayObject::append ( mixed $value )
Appends a new value as the last element.
Note:
This method cannot be called when the ArrayObject was constructed from an object. Use ArrayObject::offsetSet() instead.
source http://php.net/manual/en/arrayobject.append.php
The reason i'm asking this now is, later on when needing to delete items from this list how will i find what i'm looking for? can i use in_array() on this object.
I apologize in advance for these questions that might seem dumb to you, but keep in mind I'm still learning some of the more technical things. Thank you
There's nothing in your first snippet that would require ArrayObject. KISS and use simple arrays: array_push($this->items,$add); or $this->items []= $add; are both fine.
As a side note, there's a discrepancy between calculateTotal and add in your code: you have to decide whether you want your item structures to be arrays ($item['price']) or objects ($item->price). My advice is to use arrays, but that's really up to you.
Related
I need a bit of help ordering a SimpleXML array in an alphabetical order using one of it's attribute ($url). I have the following code that generate a page:
<?php
$xml = simplexml_load_file($xml_url);
$ids = array();
foreach($xml->list as $id) {
$ids[] = $id;
}
//It works but randomize instead of sorting alphabetically
usort($ids, function ($a, $b) {
return strnatcmp($a['url'], $b['url']);
});
foreach ($ids as $id) {
PopulatePage($id);
}
function PopulatePage($id) {
$url = $id->url;
$img = $id->img;
//OTHER CODES TO GENERATE THE PAGE
}?>
QUESTION RESOLVED!
There is no conversion needed, you already have an array which you can sort, you just need to understand how usort callbacks work. Each of the items in your $ids array is a SimpleXMLElement object, and each time your callback is run, it will be given two of those objects to compare. Those objects will be exactly the same as in the existing PopulatePage function, so accessing the URL needs to happen exactly as it does there ($url = $id->url;) not using a different notation ($id['url']).
To make it more explicit, let's write a named function with lots of clear variable names:
function CompareTwoIds(SimpleXMLElement $left_id, SimpleXMLElement $right_id): int {
$left_url = $left_id->url;
$right_url = $right_id->url;
return strncatcmp($left_url, $right_url);
}
Now you can test calling that function manually, and use it as the callback when you're happy:
usort($ids, 'CompareTwoIds');
Once you're comfortable with the principles, you may decide to skip the extra verbosity and just write this, which is completely equivalent:
usort($ids, fn($a,$b) => strncatcmp($a->url, $b->url));
I have a problem occurring in one function, for me it's strange because I thought that the behaviour of objects were different. The function is:
function getMessages($imapCon)
{
$messageHeaders = array();
$tempObj = new stdClass();
$totalMessages = imap_num_msg($imapCon);
for ($i = $totalMessages; $i > 0; $i--)
{
$headers = imap_headerinfo($imapCon, $i);
$tempObj->Unseen = $headers->Unseen;
$tempObj->fromaddress = $headers->fromaddress;
$tempObj->Date = $headers->Date;
$tempObj->Subject = $headers->Subject;
$tempObj->uid = imap_uid($imapCon, $i);
array_push($messageHeaders, $tempObj);
}
return json_encode($messageHeaders);
}
In the json encoded, I get the same values for all properties (Unseen, fromaddress, Date...). The properties are set correct, but the values are duplicated. Why?
If I do something like:
for ($i = $totalMessages; $i > 0; $i--)
{
$tempObj = new stdClass();
...
array_push($messageHeaders, $tempObj);
unset($tempObj);
}
return json_encode($messageHeaders);
}
declaring the object inside the for, it works. But I believe this is a poor fix and nor the right thing to do...
Creating a new $tempObj inside the loop is the right way. When you add this object into array, it's not copied, but a pointer to it is added into the array. Check this documentation - http://php.net/manual/en/language.oop5.basic.php#example-191 (look at the simple assignment, ignore the $reference variable for now).
So you end up with array containing the whole bunch of links pointing to the same object. But if you create a new $tempObj inside the loop, all objects will be different.
Alternatively, you can do this:
array_push($messageHeaders, clone($tempObj));
but although this will equally work in this case, it may not work if the $tempObj would have more complex structure, such as instances of othe classes as properties of $tempObj.
On a side note, in PHP4 your code would work as you expected as PHP4 was copying actual objects on assignment instead of just pointers as PHP5 does.
It looks like you are just pushing a reference into the $messageHeaders array each time, but you are reassigning the data on the same instance. Not sure where you got the idea that it was wrong to create a new $tempObj on each iteration but that is one way you could solve this. Another way would be to just add to the $messageHeaders array directly like this:
$messageHeaders[] = array(
'Unseen' => $headers->Unseen,
'fromaddress' => $headers->fromaddress,
'Date' => $headers->Date,
'Subject' => $headers->Subject,
'uid' => imap_uid($imapCon, $i)
);
I got a 2d-array containing a "column" on which this whole array is to be sorted. As I learned here, it is quite straightforward using array_multisort. My problem is, that this to be sorted over column contains values that needs to be compared in an unusual way. So I thought of something like this:
function main(){
$toBeSorted = array(array(...), ..., array(...));
$sortColumnIndex = n;
$sort_column = array();
//Code copied from provided link
foreach ($toBeSorted as $row)
$sort_column []= $row[$sortColumnIndex];
array_multisort($this->comparator(),$sort_column, $toBeSorted);
}
function comparator(a,b){
return 1;
}
As you can see, I want to pass my comparator to that sort-function. I probably think to much in a non-php way.
There is the usort function, which sorts by using a callback.
Otherwise you could have a look at the array_walk and array_walk_recursive functions, which iterate over an array and apply a function to every member.
I solved it by transforming my sorting space in one, that array_multisort can handle:
...
$sortColumn = array();
foreach($toBeSorted as $value){
$sortColumn[] = $this->transform($value);
}
array_multisort($sortColumn, $toBeSorted);
...
my transformation function simply does everything I imagined the callback would do.
function transform($value){
//i.e. return real part of complex number
//or parse strings or any kind of strange datatypes
}
If I wanted to create an array in PHP with the following format, what would be the best way to approach it? Basically I want to declare the array beforehand, and then be able to add the values to person_id, name and age.
'person_id' => array('name'=>'jonah', 'age'=> 35)
To the first answer #Joe, first of all, your class doesn't support encapsulation since your attributes are public. Also, for someone who doesn't know how to create an array, this concept may be a bit complicated.
For the answer, changing a bit the class provided by #Joe, PHP provide a simple way of using arrays:
If you need many rows for this array, each row has a number, if not, remove the [0] for only one entry.
$persons = array();
$persons[0]['person_id'] = 1;
$persons[0]['name'] = 'John';
$persons[0]['age'] = '27';
Depending on how you want to use it, you could make a simple object:
class Person
{
public $person_id;
public $name;
public $age;
}
$person = new Person; // make the object beforehand
$person->person_id = 123; // their id
$person->name = 'Joe'; // my name
$person->age = 21; // yeah, right
This is virtually identical to an array (in terms of how it's used) except for:
Instead of new array() you use new Person (no brackets)
Instead of accessing items with ['item'] you use ->item
You can start with an empty array:
$arr = Array();
Then add stuff to that array:
$arr['person_id'] = Array();
$arr['person_id']['name'] = "jonah";
$arr['person_id']['age'] = 35;
Is it possible to have an AND in a foreach loop?
For Example,
foreach ($bookmarks_latest as $bookmark AND $tags_latest as $tags)
You can always use a loop counter to access the same index in the second array as you are accessing in the foreach loop (i hope that makes sense).
For example:-
$i = 0;
foreach($bookmarks_latest as $bookmark){
$result['bookmark'] = $bookmark;
$result['tag'] = $tags_latest[$i];
$i++;
}
That should achieve what you are trying to do, otherwise use the approach sugested by dark_charlie.
In PHP 5 >= 5.3 you can use MultipleIterator.
Short answer: no. You can always put the bookmarks and tags into one array and iterate over it.
Or you could also do this:
reset($bookmarks_latest);
reset($tags_latest);
while ((list(, $bookmark) = each($bookmarks_latest)) && (list(,$tag) = each($tags_latest)) {
// Your code here that uses $bookmark and $tag
}
EDIT:
The requested example for the one-array solution:
class BookmarkWithTag {
public var $bookmark;
public var $tag;
}
// Use the class, fill instances to the array $tagsAndBookmarks
foreach ($tagsAndBookmarks as $bookmarkWithTag) {
$tag = $bookmarkWithTag->tag;
$bookmark = $bookmarkWithTag->bookmark;
}
you can't do that.
but you can
<?php
foreach($keyval as $key => $val) {
// something with $key and $val
}
the above example works really well if you have a hash type array but if you have nested values in the array I recommend you:
or option 2
<?php
foreach ($keyval as $kv) {
list($val1, $val2, $valn) = $kv;
}
No, but there are many ways to do this, e.g:
reset($tags_latest);
foreach ($bookmarks_latest as $bookmark){
$tags = current($tags_latest); next($tags_latest);
// here you can use $bookmark and $tags
}
No. No, it is not.
You'll have to manually write out a loop that uses indexes or internal pointers to traverse both arrays at the same time.
Yes, for completeness:
foreach (array_combine($bookmarks_latest, $tags_latest) as $bookm=>$tag)
That would be the native way to get what you want. But it only works if both input arrays have the exact same length, obviously.
(Using a separate iteration key is the more common approach however.)