PHP: Create array of arrays, ignoring empty arrays - php

I need to create an array of arrays.
I have been using array_map(null,$a,$b,$c) to do this and it works fine, however, it doesn't work if one of the mapped arrays doesn't exist.
To get around this problem I have used:
$myArray= array();
if (isset($a)) {
array_push($myArray,$a);
}
if (isset($b)) {
array_push($myArray,$b);
}
if (isset($c)) {
array_push($myArray,$c);
}
Is there a more elegant/shorter method of writing this?
I've tried applying some functions via array_map($function,$a,$b,$c) but with no luck.

$myArray = array_filter(array($a, $b, $c));

You could use the following function:
function joinArrays(){
$arrays = func_get_args();
$output = array();
foreach($arrays as $array){
if(!empty($array)) array_push($output, $array);
}
return $output;
}
call like: joinArrays($a, $b, $c, etc..);

Related

Merge two arrays in PHP without changing the structure of the first array

$arr1 = array('foo'=>array('green'=>10, 'flowers'=>20), 'bar'=>20);
$arr2 = array('red'=>'roses', 'blue'=>'sky', foo=>array('flowers'=>15), 'bar'=>array('demo'=>'asdf'));
Desired result of the merge:
array('foo'=>array('green'=>10, 'flowers'=>15), 'bar'=>array('demo'=>'asdf'));
I have written a recursive function for this purpose, but I wonder if there is a more elegant way in PHP to achieve this.
This is my function:
function array_overwrite_recursive($arr1, $arr2) {
foreach($arr1 As $k=>$v) {
if(is_array($arr1[$k])) {
$arr1[$k] = array_overwrite_recursive($arr1[$k], $arr2[$k]);
} else {
if(isset($arr2[$k])) $arr1[$k]=$arr2[$k];
}
}
return $arr1;
}

PHP - dynamically add dimensions to array

I have a :
$value = "val";
I also have an array :
$keys = ['key1', 'key2', 'key3'...]
The keys in that array are dynamically generated, and can go from 2 to 10 or more entries.
My goal is getting this :
$array['key1']['key2']['key3']... = $value;
How can I do that ?
Thanks
The easiest, and least messy way (ie not using references) would be to use a recursive function:
function addArrayLevels(array $keys, array $target)
{
if ($keys) {
$key = array_shift($keys);
$target[$key] = addArrayLevels($keys, []);
}
return $target;
}
//usage
$keys = range(1, 10);
$subArrays = addARrayLevels($keys, []);
It works as you can see here.
How it works is really quite simple:
if ($keys) {: if there's a key left to be added
$key = array_shift($keys); shift the first element from the array
$target[$key] = addArrayLevels($keys, []);: add the index to $target, and call the same function again with $keys (after having removed the first value). These recursive calls will go on until $keys is empty, and the function simply returns an empty array
The downsides:
Recursion can be tricky to get your head round at first, especially in complex functions, in code you didn't write, but document it well and you should be fine
The pro's:
It's more flexible (you can use $target as a sort of default/final assignment variable, with little effort (will add example below if I find the time)
No reference mess and risks to deal with
Example using adaptation of the function above to assign value at "lowest" level:
function addArrayLevels(array $keys, $value)
{
$return = [];
$key = array_shift($keys);
if ($keys) {
$return[$key] = addArrayLevels($keys, $value);
} else {
$return[$key] = $value;
}
return $return;
}
$keys = range(1, 10);
$subArrays = addARrayLevels($keys, 'innerValue');
var_dump($subArrays);
Demo
I don't think that there is built-in function for that but you can do that with simple foreach and references.
$newArray = [];
$keys = ['key1', 'key2', 'key3'];
$reference =& $newArray;
foreach ($keys as $key) {
$reference[$key] = [];
$reference =& $reference[$key];
}
unset($reference);
var_dump($newArray);

PHP array_walk_recursive: two approaches, different result

Given the following setup:
$storer = array();
$arr = array(1, 2, 3);
I'm curious why this does not write to $storer...
array_walk_recursive($arr, function($val, $key) {
global $storer;
$storer[] = 'foo';
});
print_r($storer); //no change - empty
..but this does:
array_walk_recursive($arr, function($val, $key) use (&$storer) {
$storer[] = 'foo';
});
print_r($storer); //three items, all 'foo'
Can anyone enlighten me? In a user function I would expect global to provide read/write access.
After pulling my hair out trying to get a flattened array with keys this works:
$result = array();
array_walk_recursive($inputarray,function($v, $k) use (&$result){ $result[$k] = $v; });
$inputarray = $result;
I hope someone finds this and it helps.

Iterate through an array, looking for keys that match the values of another array

This is probably a simple question...
I have a multidimensional array called $form. I need to iterate through the array, looking for specific keys that match another array values and then perform an action in those keys.
$a = 'theme_select';
$b = 'timezone';
$c = 'contact';
$d = 'something_else';
$arr = array();
$arr = ($a, $b, $c, $d);
foreach($form as $form_key=>$form_val){
foreach($arr as $include) {
if ($form_key == $include) {
//some action
}
}
}
Is this the best way to accomplish this? The reason I'm asking is that $form can be quite big and I fear that page loading can become quite slow.
Have a look at the array_intersect_key() function
$a = 'theme_select';
$b = 'timezone';
$c = 'contact';
$d = 'something_else';
$arr = array_fill_keys(array($a, $b, $c, $d),1);
$matchingKeys = array_intersect_keys($form,$arr);
foreach($matchingKeys as $key => $value) {
...
}

How to access elements in an array returned from a function?

I need to return multiple values from a function, therefore I have added them to an array and returned the array.
<?
function data(){
$a = "abc";
$b = "def";
$c = "ghi";
return array($a, $b, $c);
}
?>
How can I receive the values of $a, $b, $c by calling the above function?
You can add array keys to your return values and then use these keys to print the array values, as shown here:
function data() {
$out['a'] = "abc";
$out['b'] = "def";
$out['c'] = "ghi";
return $out;
}
$data = data();
echo $data['a'];
echo $data['b'];
echo $data['c'];
you can do this:
list($a, $b, $c) = data();
print "$a $b $c"; // "abc def ghi"
function give_array(){
$a = "abc";
$b = "def";
$c = "ghi";
return compact('a','b','c');
}
$my_array = give_array();
http://php.net/manual/en/function.compact.php
The data function is returning an array, so you can access the result of the function in the same way as you would normally access elements of an array:
<?php
...
$result = data();
$a = $result[0];
$b = $result[1];
$c = $result[2];
Or you could use the list() function, as #fredrik recommends, to do the same thing in a line.
<?php
function demo($val,$val1){
return $arr=array("value"=>$val,"value1"=>$val1);
}
$arr_rec=demo(25,30);
echo $arr_rec["value"];
echo $arr_rec["value1"];
?>
$array = data();
print_r($array);
From PHP 5.4 you can take advantage of array dereferencing and do something like this:
<?
function data()
{
$retr_arr["a"] = "abc";
$retr_arr["b"] = "def";
$retr_arr["c"] = "ghi";
return $retr_arr;
}
$a = data()["a"]; //$a = "abc"
$b = data()["b"]; //$b = "def"
$c = data()["c"]; //$c = "ghi"
?>
Maybe this is what you searched for :
function data() {
// your code
return $array;
}
$var = data();
foreach($var as $value) {
echo $value;
}
In order to get the values of each variable, you need to treat the function as you would an array:
function data() {
$a = "abc";
$b = "def";
$c = "ghi";
return array($a, $b, $c);
}
// Assign a variable to the array;
// I selected $dataArray (could be any name).
$dataArray = data();
list($a, $b, $c) = $dataArray;
echo $a . " ". $b . " " . $c;
//if you just need 1 variable out of 3;
list(, $b, ) = $dataArray;
echo $b;
//Important not to forget the commas in the list(, $b,).
here is the best way in a similar function
function cart_stats($cart_id){
$sql = "select sum(price) sum_bids, count(*) total_bids from carts_bids where cart_id = '$cart_id'";
$rs = mysql_query($sql);
$row = mysql_fetch_object($rs);
$total_bids = $row->total_bids;
$sum_bids = $row->sum_bids;
$avarage = $sum_bids/$total_bids;
$array["total_bids"] = "$total_bids";
$array["avarage"] = " $avarage";
return $array;
}
and you get the array data like this
$data = cart_stats($_GET['id']);
<?=$data['total_bids']?>
All of the above seems to be outdated since PHP 7.1., as #leninzprahy mentioned in a comment.
If you are looking for a simple way to access values returned in an array like you would in python, this is the syntax to use:
[$a, $b, $c] = data();
I think the best way to do it is to create a global var array. Then do whatever you want to it inside the function data by passing it as a reference. No need to return anything too.
$array = array("white", "black", "yellow");
echo $array[0]; //this echo white
data($array);
function data(&$passArray){ //<<notice &
$passArray[0] = "orange";
}
echo $array[0]; //this now echo orange
This is what I did inside the yii framewok:
public function servicesQuery($section){
$data = Yii::app()->db->createCommand()
->select('*')
->from('services')
->where("section='$section'")
->queryAll();
return $data;
}
then inside my view file:
<?php $consultation = $this->servicesQuery("consultation"); ?> ?>
<?php foreach($consultation as $consul): ?>
<span class="text-1"><?php echo $consul['content']; ?></span>
<?php endforeach;?>
What I am doing grabbing a cretin part of the table i have selected. should work for just php minus the "Yii" way for the db
The underlying problem revolves around accessing the data within the array, as Felix Kling points out in the first response.
In the following code, I've accessed the values of the array with the print and echo constructs.
function data()
{
$a = "abc";
$b = "def";
$c = "ghi";
$array = array($a, $b, $c);
print_r($array);//outputs the key/value pair
echo "<br>";
echo $array[0].$array[1].$array[2];//outputs a concatenation of the values
}
data();
I was looking for an easier method than i'm using but it isn't answered in this post. However, my method works and i don't use any of the aforementioned methods:
function MyFunction() {
$lookyHere = array(
'value1' => array('valuehere'),
'entry2' => array('valuehere')
);
return $lookyHere;
}
I have no problems with my function. I read the data in a loop to display my associated data. I have no idea why anyone would suggest the above methods. If you are looking to store multiple arrays in one file but not have all of them loaded, then use my function method above. Otherwise, all of the arrays will load on the page, thus, slowing down your site. I came up with this code to store all of my arrays in one file and use individual arrays when needed.
Your function is:
function data(){
$a = "abc";
$b = "def";
$c = "ghi";
return array($a, $b, $c);
}
It returns an array where position 0 is $a, position 1 is $b and position 2 is $c. You can therefore access $a by doing just this:
data()[0]
If you do $myvar = data()[0] and print $myvar, you will get "abc", which was the value assigned to $a inside the function.

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