My problem is, i have a 2D Array and i want to override the value of an element that was set.
My code is as follows:
$indes="-1";
$inupccode="-1";
$inuomcode="-1";
$instdpack="-1";
$inweight="-1";
$inlength="-1";
$inwidth="-1";
$inheight="-1";
$inunitprice="-1";
$infamcode="-1";
$basicInfo = array(array($indes,"prdes1_35", $inupccode,
"prupc#_2", $inuomcode,"prwuts_3-1",
$instdpack,"prwuns_12", $inweight,
"prgrwt_11", $inlength,"prlong_7",
$inwidth,"prwide_7", $inheight,"prhigh_7",
$inunitprice,"prprce_12", $infamcode,"proga2"));
echo "before";
print_r($basicInfo);
foreach($basicInfo as $value){
foreach ($value as $id){
if($id == "prdes1_35"){
$value = 2;
}
}
}
echo "after";
print_r($basicInfo);
In the code for the value of $indes i would like to change from -1 to 2 and the reminder array value must remain as "-1". How can i achieve this?
Biggest problem first: I dont think your code does what you intent to achieve. Are you sure you understand (multi dimensional) arrays?
The other issue is the way you try to change $value. Please check this post:
(https://stackoverflow.com/questions/15024616/php-foreach-change-original-array-values)
for information on how to change an array you run through with foreach.
Simplest solution for you would be:
foreach($basicInfo as &$value){
foreach ($value as $id){
if($id == "prdes1_35"){
$value = 2;
}
}
}
Mind the ampersand (&) before the $value variable. The referenced post an the link in there hold all the explanation necessary to understand what it means.
Perfomancewise this would be the best solution, especially when your array gets big:
foreach($basicInfo as $key => $value){
foreach ($value as $id){
if($id == "prdes1_35"){
$basicInfo[$key][$value] = 2;
}
}
}
NOTE: I did not change your codes logic (that is broken, I assume). I just demonstrated how to change a value when iterating through an array with foreach.
Related
I have this code
if (isset($_POST['submit2']))
{
foreach ($_POST['check_list'] as $key) {
$input = implode(",", $key);
}
} /*end is isset $_POST['submit2'] */
echo $input;
it produces the error " implode(): Invalid arguments passed " when I change the implode arguments to implode(",", $_POST['check_list']) it works as intended.
Can someone clarify why? As far as I understand the $key variable should be the same as the $_POST['submit2'] isn't that what the as in the foreach does?
Sorry if it's a silly question, I'm self taught and sometimes details like that are hard to find online.
You seem confused at several levels, so let me clarify some of them:
You said 'As far as I understand the $key variable should be the same as the $_POST['submit2'] isn't that what the as in the foreach does?'. The answers are NO and NO:
The $key variable outside the foreach loop will contain the last element of the array that's stored in $_POST['check_list'], $_POST['submit2'] seems to be only used to check if is set and nothing else in your piece of code. What foreach does is to traverse any iterator variable (an array in your case) and set the current item in a variable ($key) in your case. So after the loop, $key will contain the last element of that array. For more information refer to the docs: [http://php.net/manual/en/control-structures.foreach.php]
implode expects the second parameter to be an array, it seems you're not providing an array, but any other type. Is the last item of $_POST['check_list'] actually an array?
If you're trying to 'glue' together all items of $_POST['check_list'], you don't need to iterate, you just use implode on that one: $input = implode(",", $_POST['check_list']);. Otherwise, i'm not sure what are you trying to do.
Maybe if you explain what are you trying to do, we can help better.
Foreach already iterates trough your values. You can either get the value and echo it from there or you can add it to another array input if thats what you need:
if (isset($_POST['submit2']))
{
foreach ($_POST['check_list'] as $key => $value) {
$input[] = 'Value #'. $key .' is ' . $value;
}
}
echo implode(",", $input);
You are saying that $_POST['check_list'] is an array if implode() works on it, so no need to loop to get individual items. To implode() the values:
echo implode(',', $_POST['check_list']);
To implode() the keys:
echo implode(',', array_keys($_POST['check_list']));
foreach() iterates over an array to expose each item and get the individual values and optionally keys one at a time:
foreach($_POST['check_list'] as $key => $val) {
echo "$key = $value<br />";
}
implode function needs array as second argument. You are passing string value as second argument. That's why it's not working.
Upon posting a form using _GET I would like to get the input name
See below part of url upon submit
.php?14=0&15=0&16=0&17=0&18=0&19=0
I know how to get the variable E.G:
$14=$_GET["14"];
Which is 0
However is it possible to do this and get the input name (eg 14) and then turn these into variables? (To save the input name to the DB)
To get all the $_GET parameters, you can do:
foreach($_GET as $key => $value){
echo "Key is $key and value is $value<br>";
}
This will output each key (14, 15, 16 etc) and value (0, 0, 0 etc).
To bind a variable name with a variable string, look at variable variables:
foreach($_GET as $key => $value){
$$key = $value;
}
As a result, you will have the following variables with the following values:
$14 = 0;
$15 = 0;
$16 = 0;
// etc...
Alternatively (as you don't necessarily know what the key/value pairs would be), you could create an empty array and add these keys and values to it:
foreach($_GET as $k => $v){
$arr[$k] = $v;
}
The resulting array will be:
$arr[14] = 0;
$arr[15] = 0;
$arr[16] = 0;
// etc...
Solution using single loop (Update):
If you're just using question/answer single time you can do it in single loop like this,
<?php
foreach($_GET as $key => $value){
$question = $key;
$answer = $value;
// Save question and answer accordingly.
}
If you will be using question answer to perform other things, use the following method.
You can get all the keys using array_keys(), where $_GET is an array.
Use it like this,
<?php
$keys=array_keys($_GET);
print_r($keys); // this will print all the keys
foreach($keys as $key) {
// access each key here with $key
}
Update:
You can make a pair of question,answer array and put it in the main array to insert it in the database like this,
<?php
$mainArray=array();
$keys=array_keys($_GET);
foreach($keys as $key) {
// access each key here with $key
$questionAnswerArray=array();
$questionAnswerArray["question"]=$key;
$questionAnswerArray["answer"]=$_GET[$key];
$mainArray[]=$questionAnswerArray;
}
// Now traverse this array to insert the data in database.
foreach($mainArray as $questionanswer) {
echo $questionanswer["question"]; //prints the question
echo $questionanswer["answer"]; // prints the answer.
}
<?php
$interests[50] = array('fav_beverages' => "beer");
?>
now i need the index (i.e. 50 or whatever the index may be) from the value beer.
I tried array_search(), array_flip(), in_array(), extract(), list() to get the answer.
please do let me know if I have missed out any tricks for the above functions or any other function I`ve not listed. Answers will be greatly appreciated.
thanks for the replies. But for my disappointment it is still not working. btw I have a large pool of data like "beer");
$interests[50] = array('fav_cuisine' => "arabic");
$interests[50] = array('fav_food' => "hummus"); ?> . my approach was to get the other data like "arablic" and "hummus" from the user input "beer". So my only connection is via the index[50].Do let me know if my approach is wrong and I can access the data through other means.My senior just informed me that I`m not supposed to use loop.
This should work in your case.
$interests[50] = array('fav_beverages' => "beer");
function multi_array_search($needle, $interests){
foreach($interests as $interest){
if (array_search($needle, $interest)){
return array_search($interest, $interests);
break;
}
}
}
echo multi_array_search("beer", $interests);
If your array contains multiple sub-arrays and you don't know which one contains the value beer, then you can simply loop through the arrays, and then through the sub-arrays, to search for the value, and then return the index if it is found:
$needle = 'beer';
foreach ($interests as $index => $arr) {
foreach ($arr as $value) {
if ($value == $needle) {
echo $index;
break;
}
}
}
Demo
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Strange behavior Of foreach
Just came across this bug recently in a PHP app. Not sure what's going on.
Basically, it shows up when using a combination of two foreach (one with &, one without).
Here's a test code that reproduce the problem:
$items = array(
array('id'=>1, 'name'=>'foo', 'value'=>150),
array('id'=>2, 'name'=>'bar', 'value'=>190)
);
foreach($items as &$item)
{
$item['percentage'] = $item['value'] * 0.75;
}
var_dump($items); // All Good
foreach($items as $item)
{
var_dump($item); // Shows 1st item twice
}
The second foreach loop runs the block twice, as expected, but $item remains stuck on the first item.
I understand this is likely caused by the use of the reference & in the first loop but I don't see why it should behave like this..
Any idea? is that a bug?
Getting the same result on 5.3.8, 5.3.10 & 5.4
Firstly, it is not a bug as Rasmus said. See https://bugs.php.net/bug.php?id=29992
In this, right implementation of modifying array with its loop variable with &.
<?php
$arr = array(1, 2, 3, 4);
foreach ($arr as &$value) {
$value = $value * 2;
}
// $arr is now array(2, 4, 6, 8)
unset($value); // break the reference with the last element
var_dump($arr); // All Good
foreach($arr as $value) {
var_dump($value); // All good
}
?>
This is odd PHP behavior that's been around pretty much forever, and it happens when you mix the use of a variable as reference then not reference like you did.
I deal with it with a naming convention as follows: When I am using foreach with a &$item, I name it like &$refItem. This keeps me from mixing types.
You need to unset the pointer after using foreach with a referenced array.
http://php.net/unset
This may be something that look more understand the problem of foreach
$last_value_of_first_foreach = 1;
$item = 2;
$c = 3;
$item = &$last_value_of_first_foreach ; // Think that this statement is first foreach loop
// Here $item is pointer to $last_value_of_first_foreach
// To Better understanding, let change the name ($reference_to_last_value = $item;)
now, the new loop is
$item = $c;
// Here, what it do is update value where the $item pointer refer to
// (mean $last_value_of_first_foreach )
// so, at here $last_value_of_first_foreach has value of $c
Now, back to your case, from the first foreach, the $item reference to the last element of array. now, when you assign something to $item in second foreach, what it do, is put something inside that one.
In the end of first loop
$item is pointer to $items[1]
The first of second loop
it will push the first element to the location where the $item point to (that mean $items[1], so that why $items[1] is replaced by $items[0].
In case you want to prevent this one, just unset the $item variable before next time usage.
This is a normal, not a weird behavior. Just read about reference here.
When you add & in front of a variable, you store the reference to a variable. So, when you re-use it, it will also change the contents of the referenced variable.
foreach($items as &$item) // You have $item here, prefixed with &.
{
$item['percentage'] = $item['value'] * 0.75;
}
var_dump($items);
foreach($items as $item) // And your re-use it here.
{
var_dump($item);
}
To solve this, add unset($item) in the 1st loop:
foreach($items as &$item)
{
$item['percentage'] = $item['value'] * 0.75;
unset($item); // add this, because you use &$item previously.
}
So I don't think I'm making full use of the foreach loop. Here is how I understand foreach.
It goes like foreach(arrayyouwanttoloopthrough as onevalueofthatarray)
No counter or incrementing required, it automatically pulls an array, value by value each loop, and for that loop it calls the value whatever is after the "as".
Stops once it's done with the array.
Should basically replace "for", as long as dealing with an array.
So something I try to do a lot with foreach is modify the array values in the looping array. But in the end I keep finding I have to use a for loop for that type of thing.
So lets say that I have an array (thing1, thing2, thing3, thing4) and I wanted to change it....lets say to all "BLAH", with a number at the end, I'd do
$counter = 0;
foreach($array as $changeval){
$counter++;
$changeval = "BLAH".$counter;
}
I would think that would change it because $changeval should be whatever value it's at for the array, right? But it doesn't. The only way I could find to do that in a] foreach is to set a counter (like above), and use the array with the index of counter. But to do that I'd have to set the counter outside the loop, and it's not even always reliable. For that I'd think it would be better to use a for loop instead of foreach.
So why would you use foreach over for? I think I'm missing something here because foreach has GOT to be able to change values...
Thanks
OH HEY One more thing. Are variables set in loops (like i, or key) accessible outside the loop? If I have 2 foreach loops like
foreach(thing as value)
would I have to make the second one
foreach(thing2 as value2) ]
or else it would have some problems?
You can use a reference variable instead:
foreach ($array as &$value)
{
$value = "foo";
}
Now the array is full of foo (note the & before $value).
Normally, the loop variable simply contains a copy of the corresponding array element, but the & (ampersand) tells PHP to make it a reference to the actual array element, rather than just a copy; hence you can modify it.
However, as #Tadeck says below, you should be careful in this case to destroy the reference after the loop has finished, since $value will still point to the final element in the array (so it's possible to accidentally modify it). Do this with unset:
unset($value);
The other option would be to use the $key => $value syntax:
foreach ($array as $key => $value)
{
$array[$key] = "foo";
}
To answer your second question: yes, they are subsequently accessible outside the loop, which is why it's good practice to use unset when using reference loop variables as in my first example. However, there's no need to use new variable names in subsequent loops, since the old ones will just be overwritten (with no unwanted consequences).
You want to pass by reference:
$arr = array(1, 2, 3, 4);
foreach ($arr as &$value)
{
$value = $value * 2;
}
// $arr is now array(2, 4, 6, 8)
The extended foreach syntax is like this:
foreach ($array as $key => $value) {
}
Using the $key, you can index the original array:
foreach ($array as $key => $value) {
$array[$key] = "BLAH";
}
Incrementing from 0 to ...
foreach($array as $changeval){
if (!isset($counter)) { $counter = 0; }
$counter++;
$changeval = "BLAH".$counter;
}
Using the index/key of the ARRAY
foreach($array as $key => $changeval){
$changeval = "BLAH".$key;
}
You can use the key when looping with foreach:
foreach ($array as $key => $value)
{
$array[$key] = "foo";
}
But note that using a reference like Will suggested will be faster for such a case - but anyway, the $key => $value-syntax is quite useful sometimes.