I don't really know how to decribe this problem, so I'm sorry if the title is a bit unclear.
I got an object with array fields. I got the name of these fields stored in a variable and I want to reach an element in one of those array fields. e.g.
$field_name = 'array_field';
$object = new stdClass();
$object->array_field= array('this', 'is', 'an', 'array);
I know i can access the array with $object->$field_name, but now I want to access a value by key in the array while accessing it with the $field_name variable. e.g.(that obviously does not work) $object->$field_name[0]
I think, you should use something like the following:
$object->{$field_name}[0]
It's described in details in "Variable variables" section of PHP manual: http://www.php.net/manual/en/language.variables.variable.php
BTW, according to my experience, such way of fields manipulation may lead to code obscurity - I'd recommend to use associative arrays, if possible.
Try this:
$object->{$field_name}[0]
Related
I have an array named 'users' in which I am storing some variables as you see below.I want to verify if the 'nume' (name) value already existing in this array is the same as the value introduced by a person in a search box. I've tried some methods but I haven't obtained the wanted result. I think it is something obvious I can't see at the moment.
EDIT : The image is the result of var_dump() of my code. I am using it for people to understand what I want to know.
it's simple, try that:
$searchValue = 'victor';
$index = array_search($searchValue, array_column($users, 'nume'));
I want to convert two different PHP tags into a single PHP tag.This may sound a little weird but recently I found a question like this and answer with correct marked.
I can't find I'm currently lost address.
My question:
for example;
$gates = array('t1','t2','t3',t4','t5');
$openGates-> and $gates merge.
Result:
$openGates->t1; or t2,t3.
If I remember correctly, the answer to the problem I found before was;
$openGates->{$gates}; like this. I not sure
How can I do that?
You seem to be confusing objects with arrays. Arrays simply contain data, unless you create them with keys also. Such as:
$gates = array('t1'=>true,'t2'=>false,'t3'=>"maybe",'t4'=>0,'t5'=>50);
Matthew Page is correct in that you should look up PHP OOP for a solution.
That being said, you can cast your array to an object providing it has both keys and values:
$gates = (object) array('t1'=>true,'t2'=>false,'t3'=>"maybe",'t4'=>0,'t5'=>50);
or
$openGates = (object) $gates;
This will allow you to access 'properties' of the object in the way you have demonstrated:
echo $openGates->t1;, for example. The -> operator only applies to objects, which are instances of classes, not arrays.
If you do cast your array to the type of object, be sure that you have both keys and values.
It's not simple for newbie programmer...
At first:
$gates = array('t1','t2','t3','t4','t5');
It's Array
$openGates->
This is class instance. Btw. You can retrieve class instance var like $className->varName
You can't simple merge array and class instance. But you can create new class instance variables by loop.
foreach($gates as $gateKey=>$gateVal) {
$openGates->$gatesVal = NULL;
}
But I think it's, in result should be like that:
$gates = array('t1'=>'opened','t2'=>'closed','t3'=>'closed','t4'=>'opened','t5'=>'opened');
foreach($gates as $gateKey=>$gateVal) {
$openGates->$gateKey = $gateVal;
}
echo $openGates->t1;
// or
foreach($gates as $key=>$val) {
echo $openGates->$key.PHP_EOL;
}
Btw you can simple set $openGates->gates = $gates; and call it like echo $openGates->gates['t1'];
I need to create an association between an Array and a Number; as PHP lacks a Map type, I am trying using an array to achieve this:
$rowNumberbyRow = array();
$rowNumberByRow[$rowData] = $rowNumber;
However, when I evaluate the code, I get the following Error:
Warning: Illegal offset type
Just to note, the data stored in the array ($rowData) does not have any 'unique' values that I can use as a key for the $rowNumberByRow Array.
Thanks!
UPDATE:
To answer some of my commenters, I am trying to create a lookup table so that my application can find the row number for a given row in O(1) time.
PHP does have a map Class: It's called SplObjectStorage. It can be accessed with exactly the same syntax as a general array is (see Example #2 on the reference).
But to use the class you will have to use the ArrayObject class instead of arrays. It is handled exactly the same way arrays are and you can construct instances from arrays (e.g. $arrayObject = new ArrayObject($array)).
If you don't want to use those classes, you can also just create a function that creates unique hash-strings for your indexes. For example:
function myHash($array){
return implode('|',$array);
}
$rowNumberByRow[myHash($array)] = $rowNumber;
You will of course have to make sure that your hashes are indeed unique, and I would strongly suggest you use the SplObjectStorage and maybe read a little bit more about the SPL classes of php.
Why not just store the row number in the array? e.g:
$rowData['rowNumber'] = $rowNumber;
You could instead serialize the array, e.g:
$rowNumberByRow[serialize($rowData)] = $rowNumber;
However that's pretty inefficient.
In php you can use only scalar values as an array keys.
If your $rowNumber is unique - then you'd try to use the opposite relation direction. If it is not unique - then you don't have any possible solution I know.
The answer has been alredy given and accepted, but while i was searching for a similar problem, i found this question, and i felt like i should drop a line: when someone wants to use an array with values as keys for another array, it would be useful to use the function array_combine.
If i got the arrays correctly, you could use:
$rowNumberByRow = array_combine($rowData, $rowNumber);
Please take a look at the PHP manual to see some info about permitted values for the keys :)
So, I need the actual variable name "varName" from global space. This function is actually a method inside a class.
Code is arbitrary for simplicity
$varName = 'what ever';
public function save($var)
{
$i[varName goes here] = $var;
}
I don't know if this is even possible, but I think maybe with a callback?
If it's a global variable, you might be able to find out the original name with:
$varname = array_search($var, $GLOBALS);
But that's not overly reliable; a best guess. If two global variables would contain the same value, you would just receive the name of either of them.
Read about $GLOBALS variable in the documentation.
This is probably what you need. Depending on the way you determine which variable you need, you can for example user array_search() to find the proper name based on the value.
Caution: $GLOBALS is about global scope's variables.
EDIT:
But this would be still a guess. You may try the following method to determine the name of the passed variable with ~100% certainty:
Pass variable to the method with reference.
Use array_search() for finding the name of the variable. If only one key matches it, you have your name. If not, go to the next step.
Save the initial value of the variable and save the list of positions at which you have found matching elements.
Change the variable's value into new one. Perform another search based on new value and get positions that are also in the list of positions from point no. 3.
At this point you have probably found the name of the variable you are looking for.
But...
Is it really needed? I suggest that you should look for simpler solution, some better encapsulation of your code.
Ps. array_search() actually returns no more than one key (see documentation). You should know that and make searching for multiple results a little more sophisticated to not skip the correct one if more than one variable matches your search criteria. (EDIT2: As mario suggested, array_intersect($GLOBALS, array($var)) will suffice)
In C, you would use a macro. I don't think there's an equivalent in PHP.
You could pass the name of the variable to the function as a string, then in the function get the variable's value from GLOBALS or eval it.
Thanks for the solution!
Here is my test:
<?php
$varName = 'what ever';
function save($var)
{
$i[array_search($var, $GLOBALS)] = $var;
print_r($i);
}
save($varName);
?>
prints:
Array
(
[varName] => what ever
)
let's assume we have an array like this
$arr=array(array('a'=>1,'b'=>2),array('c'=>3,'d'=>4));
and a reference to one of its elements
$element=&$arr[1]['c'];
My question is is it possible to get back to the original array using the reference alone?
That is to get back to the parent array in some way without knowing it by name... This would be useful to me in a more complex scenario.
No, it's certainly not possible. Being a "reference" (as PHP calls it; it's actually a copy inhibitor) doesn't help at all in that matter. You'll have to store the original array together with the element.
$elArrPair = array(
"container" => $arr,
"element" => &$arr[1]['c'],
);
This way you can change the element with $elArrPair["element"] = $newValue and still be able to access the container.
You cannot get from $element to $arr. You can use in_array() of course, but nothing about $element contains a reference to $arr.
You copy the contect from one variable to another, nothing else, there is no connection between the two variables.