Hello i got a question, i have a session array called 'addToCart', in there are multiple arrays with various id's, i would like to loop through these arrays with a foreach regardless of what the id name is. Does anyone know how i would approach this?
Does the following construction satisfy your needs?
foreach ($addToChart as $key=>$value){
// do anything you want with $key and $value
}
If you need to check "sub-arrays", you can check $value with is_array() function and add one more foreach loop inside.
Related
This question already has answers here:
How to modify an array's values by a foreach loop?
(2 answers)
Closed 4 months ago.
I was wondering if it is possible to edit the current object that's being handled within a foreach loop
I'm working with an array of objects $questions and I want to go through and look for the answers associated with that question object in my db. So for each question go fetch the answer objects and update the current $question inside my foreach loop so I can output/process elsewhere.
foreach($questions as $question){
$question['answers'] = $answers_model->get_answers_by_question_id($question['question_id']);
}
There are 2 ways of doing this
foreach($questions as $key => $question){
$questions[$key]['answers'] = $answers_model->get_answers_by_question_id($question['question_id']);
}
This way you save the key, so you can update it again in the main $questions variable
or
foreach($questions as &$question){
Adding the & will keep the $questions updated. But I would say the first one is recommended even though this is shorter (see comment by Paystey)
Per the PHP foreach documentation:
In order to be able to directly modify array elements within the loop precede $value with &. In that case the value will be assigned by reference.
Surely using array_map and if using a container implementing ArrayAccess to derive objects is just a smarter, semantic way to go about this?
Array map semantics are similar across most languages and implementations that I've seen. It's designed to return a modified array based upon input array element (high level ignoring language compile/runtime type preference); a loop is meant to perform more logic.
For retrieving objects by ID / PK, depending upon if you are using SQL or not (it seems suggested), I'd use a filter to ensure I get an array of valid PK's, then implode with comma and place into an SQL IN() clause to return the result-set. It makes one call instead of several via SQL, optimising a bit of the call->wait cycle. Most importantly my code would read well to someone from any language with a degree of competence and we don't run into mutability problems.
<?php
$arr = [0,1,2,3,4];
$arr2 = array_map(function($value) { return is_int($value) ? $value*2 : $value; }, $arr);
var_dump($arr);
var_dump($arr2);
vs
<?php
$arr = [0,1,2,3,4];
foreach($arr as $i => $item) {
$arr[$i] = is_int($item) ? $item * 2 : $item;
}
var_dump($arr);
If you know what you are doing will never have mutability problems (bearing in mind if you intend upon overwriting $arr you could always $arr = array_map and be explicit.
This question already has answers here:
How to modify an array's values by a foreach loop?
(2 answers)
Closed 4 months ago.
I was wondering if it is possible to edit the current object that's being handled within a foreach loop
I'm working with an array of objects $questions and I want to go through and look for the answers associated with that question object in my db. So for each question go fetch the answer objects and update the current $question inside my foreach loop so I can output/process elsewhere.
foreach($questions as $question){
$question['answers'] = $answers_model->get_answers_by_question_id($question['question_id']);
}
There are 2 ways of doing this
foreach($questions as $key => $question){
$questions[$key]['answers'] = $answers_model->get_answers_by_question_id($question['question_id']);
}
This way you save the key, so you can update it again in the main $questions variable
or
foreach($questions as &$question){
Adding the & will keep the $questions updated. But I would say the first one is recommended even though this is shorter (see comment by Paystey)
Per the PHP foreach documentation:
In order to be able to directly modify array elements within the loop precede $value with &. In that case the value will be assigned by reference.
Surely using array_map and if using a container implementing ArrayAccess to derive objects is just a smarter, semantic way to go about this?
Array map semantics are similar across most languages and implementations that I've seen. It's designed to return a modified array based upon input array element (high level ignoring language compile/runtime type preference); a loop is meant to perform more logic.
For retrieving objects by ID / PK, depending upon if you are using SQL or not (it seems suggested), I'd use a filter to ensure I get an array of valid PK's, then implode with comma and place into an SQL IN() clause to return the result-set. It makes one call instead of several via SQL, optimising a bit of the call->wait cycle. Most importantly my code would read well to someone from any language with a degree of competence and we don't run into mutability problems.
<?php
$arr = [0,1,2,3,4];
$arr2 = array_map(function($value) { return is_int($value) ? $value*2 : $value; }, $arr);
var_dump($arr);
var_dump($arr2);
vs
<?php
$arr = [0,1,2,3,4];
foreach($arr as $i => $item) {
$arr[$i] = is_int($item) ? $item * 2 : $item;
}
var_dump($arr);
If you know what you are doing will never have mutability problems (bearing in mind if you intend upon overwriting $arr you could always $arr = array_map and be explicit.
This question already has answers here:
How to modify an array's values by a foreach loop?
(2 answers)
Closed 4 months ago.
I was wondering if it is possible to edit the current object that's being handled within a foreach loop
I'm working with an array of objects $questions and I want to go through and look for the answers associated with that question object in my db. So for each question go fetch the answer objects and update the current $question inside my foreach loop so I can output/process elsewhere.
foreach($questions as $question){
$question['answers'] = $answers_model->get_answers_by_question_id($question['question_id']);
}
There are 2 ways of doing this
foreach($questions as $key => $question){
$questions[$key]['answers'] = $answers_model->get_answers_by_question_id($question['question_id']);
}
This way you save the key, so you can update it again in the main $questions variable
or
foreach($questions as &$question){
Adding the & will keep the $questions updated. But I would say the first one is recommended even though this is shorter (see comment by Paystey)
Per the PHP foreach documentation:
In order to be able to directly modify array elements within the loop precede $value with &. In that case the value will be assigned by reference.
Surely using array_map and if using a container implementing ArrayAccess to derive objects is just a smarter, semantic way to go about this?
Array map semantics are similar across most languages and implementations that I've seen. It's designed to return a modified array based upon input array element (high level ignoring language compile/runtime type preference); a loop is meant to perform more logic.
For retrieving objects by ID / PK, depending upon if you are using SQL or not (it seems suggested), I'd use a filter to ensure I get an array of valid PK's, then implode with comma and place into an SQL IN() clause to return the result-set. It makes one call instead of several via SQL, optimising a bit of the call->wait cycle. Most importantly my code would read well to someone from any language with a degree of competence and we don't run into mutability problems.
<?php
$arr = [0,1,2,3,4];
$arr2 = array_map(function($value) { return is_int($value) ? $value*2 : $value; }, $arr);
var_dump($arr);
var_dump($arr2);
vs
<?php
$arr = [0,1,2,3,4];
foreach($arr as $i => $item) {
$arr[$i] = is_int($item) ? $item * 2 : $item;
}
var_dump($arr);
If you know what you are doing will never have mutability problems (bearing in mind if you intend upon overwriting $arr you could always $arr = array_map and be explicit.
For example, say I post some data to a php file, but I don't know what the names of those values are. Where I would normally perform $_POST["username"] or something similar. How would I go about getting a list of all the key/value pairs within $_POST
array_keys($_POST) will give you the array keys.
You can also do this to get values with key names:
foreach ($_POST as $key => $value)
{
//do stuff;
}
However!!! Why wouldn't you know what keys are in the post? You don't want hackers putting random stuff into a post, sending it to you, and processing away. There is nothing preventing them from putting in 1000s of entries.
Use array_keys to obtain all keys in $_POST super global array:
array_keys($_POST)
Simple example:
foreach (array_keys($_POST) as $key)
{
print $_POST[$key];
}
When I send over post data I do a print_r($_POST); and I get something like this...
Array ( [gp1] => 9 )
Is there a way to get the "gp1", the name sent over as a value? I tried doing.
echo key($_POST["gp1"]);
But no luck there, I figured it would echo gp1. Is there a way to do this?
you need
print_r(array_keys($_POST));
check this for more details http://php.net/manual/en/function.array-keys.php
You could use foreach to see each key-value pair, or use array_keys to get a list of all keys.
foreach ($_POST as $key => $value) {
// Do whatever
}
Well, if you can write $_POST["gp1"] you already have the key anyway ;)
key() works differently, it takes an array as argument:
The key() function simply returns the key of the array element that's currently being pointed to by the internal pointer. It does not move the pointer in any way. If the internal pointer points beyond the end of the elements list or the array is empty, key() returns NULL.
So if you have not done anything with the array (no traversing), key($_POST) would give you the key of the first element of the array.
Maybe you want a foreach loop?
foreach($_POST as $key => $value) {
}
There are other methods to retrieve keys as to well. It depends on what you want to do.