I have a foreach loop and an if statement. If a match is found i need to ultimately break out of the foreach.
foreach ($equipxml as $equip) {
$current_device = $equip->xpath("name");
if ($current_device[0] == $device) {
// Found a match in the file.
$nodeid = $equip->id;
<break out of if and foreach here>
}
}
if is not a loop structure, so you cannot "break out of it".
You can, however, break out of the foreach by simply calling break. In your example it has the desired effect:
$device = "wanted";
foreach($equipxml as $equip) {
$current_device = $equip->xpath("name");
if ( $current_device[0] == $device ) {
// found a match in the file
$nodeid = $equip->id;
// will leave the foreach loop immediately and also the if statement
break;
some_function(); // never reached!
}
another_function(); // not executed after match/break
}
Just for completeness for others who stumble upon this question looking for an answer..
break takes an optional argument, which defines how many loop structures it should break. Example:
foreach (['1','2','3'] as $a) {
echo "$a ";
foreach (['3','2','1'] as $b) {
echo "$b ";
if ($a == $b) {
break 2; // this will break both foreach loops
}
}
echo ". "; // never reached!
}
echo "!";
Resulting output:
1 3 2 1 !
foreach($equipxml as $equip) {
$current_device = $equip->xpath("name");
if ( $current_device[0] == $device ) {
// found a match in the file
$nodeid = $equip->id;
break;
}
}
Simply use break. That will do it.
A safer way to approach breaking a foreach or while loop in PHP is to nest an incrementing counter variable and if conditional inside of the original loop. This gives you tighter control than break; which can cause havoc elsewhere on a complicated page.
Example:
// Setup a counter
$ImageCounter = 0;
// Increment through repeater fields
while ( condition ):
$ImageCounter++;
// Only print the first while instance
if ($ImageCounter == 1) {
echo 'It worked just once';
}
// Close while statement
endwhile;
For those of you landing here but searching how to break out of a loop that contains an include statement use return instead of break or continue.
<?php
for ($i=0; $i < 100; $i++) {
if (i%2 == 0) {
include(do_this_for_even.php);
}
else {
include(do_this_for_odd.php);
}
}
?>
If you want to break when being inside do_this_for_even.php you need to use return. Using break or continue will return this error: Cannot break/continue 1 level. I found more details here
Related
As there is no iterator in PHP, the only way to loop through an array without getting the length of the array is to use foreach loop.
Let say I have the following loop:
foreach ($testing_array as $testing_entry) {
$result = my_testing_api_call($testing_entry);
if ($result == 'server dead')
break;
else if ($result == 'done') {
// do something to handle success code
continue;
}
else {
sleep(5);
// I want to retry my_testing_api_call with current $testing entry, but don't know what to write
}
}
One way to do that is to use for loop instead.
for ( $i=0; $i < count($testing_array); $i++ ) {
$result = my_testing_api_call($testing_entry[$i]);
if ($result == 'server dead')
break;
else if ($result == 'done') {
// do something to handle success code
continue;
}
else {
sleep(5);
$i--; //so it will repeat the current iteration.
}
}
The problem is that the $testing_array is not originally using number as index, so I have to do some data massage to use a for loop. Is there a way I can repeat a specific iteration in a foreach loop?
Perhaps a do-while will work for you.
Untested Code:
foreach ($testing_array as $testing_entry) {
do {
$result = my_testing_api_call($testing_entry);
if ($result == 'server dead') {
break 2; // break both loops
} elseif ($result == 'done') {
// do something to handle success code
} else {
sleep(5);
// I want to retry my_testing_api_call with current $testing entry, but don't know what to write
}
} while ($result !== 'done');
}
Or a single loop structure that destroys the input array as it iterates.
Untested Code:
$result = '';
while ($testing_array && $result !== 'server dead') {
$result = my_testing_api_call(current($testing_array));
if ($result == 'done') {
// do something to handle success code
array_shift($testing_array);
} elseif ($result !== 'server dead') {
sleep(5); // I want to retry my_testing_api_call with current $testing entry, but don't know what to write
}
}
Or you can use your for loop by indexing $test_array with array_values() if you don't need the keys in your // do something.
$testing_array = array_values($testing_array);
for ($i=0, $count=count($testing_array); $i < $count; ++$i) {
$result = my_testing_api_call($testing_entry[$i]);
if ($result == 'server dead') {
break;
} else if ($result == 'done') {
// do something to handle success code
} else {
sleep(5);
--$i; //so it will repeat the current iteration.
}
}
If you do need the keys down script, but you want to use for, you could store an indexed array of keys which would allow you to use $i to access the keys and maintain data synchronicity.
My final suggestion:
Use while (key($testing_array) !== null) {...} to move the pointer without destroying elements.
Code: (Demo)
$array1 = [
"one" => 1,
"two" => 2,
"three" => 3,
"four" => 4
];
while (key($array1)!==null) { // check if the internal pointer points beyond the end of the elements list or the array is empty
$current = current($array1);
$key = key($array1);
echo "$key => $current\n"; // display current key value pair
if ($current < 3) { // an arbitrary condition
echo "\t";
$array1[$key] = ++$current; // increment the current value
} else { // current value is satisfactory
echo "\t(advance pointer)\n";
next($array1); // move pointer
}
}
Output:
one => 1
one => 2
one => 3
(advance pointer)
two => 2
two => 3
(advance pointer)
three => 3
(advance pointer)
four => 4
(advance pointer)
You are trying to handle two different things in your loop, that makes it hard to write clean control flow. You could separate the retry-logic from the result handling:
function call_api_with_retry($entry) {
do {
if (is_defined($result)) sleep(5);
$result = my_testing_api_call($entry);
} while ($result != 'done' && $result != 'server dead');
return $result;
}
foreach ($testing_array as $testing_entry) {
$result = call_api_with_retry($testing_entry);
if ($result == 'server dead')
break;
else if ($result == 'done') {
// do something to handle success code
continue;
}
}
(there might be syntax errors, it's been a while since I wrote PHP code)
To repeat a single specific iteration you need to add a control mechanism, it is not an intended behavior after all.
There are many suggestions here, all of them are kinda over-engineered.
PHP is a high level derivate of C and both languages have the 'goto' operator, it has a bad reputation because people have historically used it too much.
In the end a foreach/while loop is internally nothing else than a 'goto' operation.
Here is the code:
foreach ($array as $key => $value)
{
restart:
if ($value === 12345) goto restart;
}
That's how this should be done just keep in mind that this can cause an endless loop, like in the example.
Look at the next complicated version without goto:
foreach ($array as $key => $value) while(1)
{
if ($value === 12345) continue;
break;
}
This is essentially the same as the goto, just with more code.
If you'd want to "break" or "continue" the foreach loop you'd write "break 2" or "continue 2"
I been trying to parse statements/questions from a forum site using a DOM parser.
Its working fine, it extracts all statements in the forum. So, i tried to put a limit of extracting statements using a if condition. it still doesn't fix the problem.
I thought the problem in structuring the if condition, so i ran the loop separately and it worked..
the code goes as follows:
<?php
$i = 1;
$elementCount=0;
while(true){
require_once('dom/simple_html_dom.php');
$html = file_get_html('http://www.usmleforum.com/forum/index.php?forum=1&Page='.$i);
foreach ($html->find("tr") as $row) {
$element = $row->find('td.FootNotes2',0);
if ($element == null) { continue; }
$textNode = array_filter($element->nodes, function ($n) {
return $n->nodetype == 3; //Text node type, like in jQuery
});
if (!empty($textNode)) {
$text = current($textNode);
echo $text."<br>";
$elementCount++;
}
}
if($elementCount==12){
break;
}
$i++;
}
?>
So, even after adding the if condition for 12 statements it still runs for forever.
now the if condition alone:
<?php
$i = 1;
$elementCount=0;
while(true){
echo "harish".$i."<br>";
$elementCount++;
if($elementCount==12){
break;
}
$i++;
}
?>
It works fine, prints only 12 given statement.
Any help is appreciated...
I'm not sure you are incrementing the $elementCount correctly but since I cannot see the output of your code I'm not sure.
I would move the break statement before the $elementCount++ and also echo the $elementCount to figure out what's really going on.
The resulting code would be like this:
<?php
$i = 1;
$elementCount=0;
while(true){
require_once('dom/simple_html_dom.php');
$html = file_get_html('http://www.usmleforum.com/forum/index.php?forum=1&Page='.$i);
foreach ($html->find("tr") as $row) {
$element = $row->find('td.FootNotes2',0);
if ($element == null) { continue; }
$textNode = array_filter($element->nodes, function ($n) {
return $n->nodetype == 3; //Text node type, like in jQuery
});
if (!empty($textNode)) {
$text = current($textNode);
echo $text."<br>";
echo $elementCount;
if($elementCount===12){
break;
}
$elementCount++;
}
}
$i++;
}
?>
You should better structure your code. So you would see that you increment the elementCount inside the foreach.
As you are checking outside of the foreach for the exact elementCount it can happen, that your counter rises above 12 elements and now will run forever.
You could just change the loop to
while($elementCount < 12) {...}
So you are checking if you have less than 12 and not exactly 12 or to:
if ($elementCount >= 12) {...}
Is it possible ? Or should I end the loop and beginning another ?
foreach($array as $i)
{
if (something)
// Go back
}
It is. But not with foreach & without leaving the loop.
Here's another alternative, for good measure.
for ($i = 0; $i < count($array); $i++) {
if (condition) {
$i = 0;
}
do_stuff_with($array[$i]);
}
It is not suggested but you can use goto:
cIterator: {
foreach($array as $i)
{
if (something)
goto cIterator;
}
}
Create a function and pass the array. If something happens in the loop call the function again with the main array. Try this -
function check_loop($array) {
foreach($array as $val) {
if (something)
check_loop($array);
}
}
check_loop($array);
You can use current(), next() and prev() to loop through array and move the internal array pointer back and forth:
$items = array("apple", "box", "cat");
while($item=current($items)) {
print_r($item);
if (needToGoBack($item))
// Go to previous array item
$item = reset($items);
} else {
// Continue to next
$item = next($items);
}
}
Use continue
From the PHP docs: continue is used within looping structures to skip the rest of the current loop iteration and continue execution at the condition evaluation and then the beginning of the next iteration.
http://php.net/manual/en/control-structures.continue.php
I have a foreach loop and an if statement. If a match is found i need to ultimately break out of the foreach.
foreach ($equipxml as $equip) {
$current_device = $equip->xpath("name");
if ($current_device[0] == $device) {
// Found a match in the file.
$nodeid = $equip->id;
<break out of if and foreach here>
}
}
if is not a loop structure, so you cannot "break out of it".
You can, however, break out of the foreach by simply calling break. In your example it has the desired effect:
$device = "wanted";
foreach($equipxml as $equip) {
$current_device = $equip->xpath("name");
if ( $current_device[0] == $device ) {
// found a match in the file
$nodeid = $equip->id;
// will leave the foreach loop immediately and also the if statement
break;
some_function(); // never reached!
}
another_function(); // not executed after match/break
}
Just for completeness for others who stumble upon this question looking for an answer..
break takes an optional argument, which defines how many loop structures it should break. Example:
foreach (['1','2','3'] as $a) {
echo "$a ";
foreach (['3','2','1'] as $b) {
echo "$b ";
if ($a == $b) {
break 2; // this will break both foreach loops
}
}
echo ". "; // never reached!
}
echo "!";
Resulting output:
1 3 2 1 !
foreach($equipxml as $equip) {
$current_device = $equip->xpath("name");
if ( $current_device[0] == $device ) {
// found a match in the file
$nodeid = $equip->id;
break;
}
}
Simply use break. That will do it.
A safer way to approach breaking a foreach or while loop in PHP is to nest an incrementing counter variable and if conditional inside of the original loop. This gives you tighter control than break; which can cause havoc elsewhere on a complicated page.
Example:
// Setup a counter
$ImageCounter = 0;
// Increment through repeater fields
while ( condition ):
$ImageCounter++;
// Only print the first while instance
if ($ImageCounter == 1) {
echo 'It worked just once';
}
// Close while statement
endwhile;
For those of you landing here but searching how to break out of a loop that contains an include statement use return instead of break or continue.
<?php
for ($i=0; $i < 100; $i++) {
if (i%2 == 0) {
include(do_this_for_even.php);
}
else {
include(do_this_for_odd.php);
}
}
?>
If you want to break when being inside do_this_for_even.php you need to use return. Using break or continue will return this error: Cannot break/continue 1 level. I found more details here
I have programmed a script with the goto command but on the server where I want to execute the script there is a previous PHP version (<5.3), so I have to change the code. The structure of the code goes like that:
for($i = 0; $i < 30; $i++) // print 30 articles
{
$x = 0;
// choose a a feed from the db
// parse it
a:
foreach($feed->get_items($x, 1) as $item)
{
// create a unique id for the article of the feed
if($id == $dbid)
{
// if this id exists in the db, take the next article of the same feed which is not in the db
$x++;
goto a;
}
else
{
// print the original article you grabbed
}
} // end of foreach
} // end of for
I have tested everything. Do you have any ideas how can I retransform this code without goto in order to be executed properly???
This questions demonstrates why goto should be avoided. It lets you get away without thinking about the algorithm enough.
The standard way to do this is with a flag. I hope you were not expecting a "herezthecode kthxbai" sort of an answer, but in this case the best way to explain it would be to write the code -
for($i=0;$i<30;$++){
$x=0;
do {
$found = false;
foreach($feed->get_items($x,1) as $item){
// get $id
if($id==$dbid){
$found = true;
break;
}else{
// other things
}
}
$x++;
} while($found);
}
Without knowing how the ->get_items() call behaves you could use this brute-force method in lieu of the goto-switch:
for($i = 0; $i < 30; $i++)
{
$x = 0;
$a = 1;
while ($a--)
foreach($feed->get_items($x, 1) as $item)
{
if($id == $dbid)
{
$x++;
$a=1; break;
}
else
{
}
} // end of foreach
} // end of for
The label gets replaced by a while and a self-fulfulling stop condition. And the goto becomes a break and resets the $a stop condition.
Something like this would probably work...
function loop(){
foreach($feed->get_items($x,1) as $item){
if($id==$dbid){
$x++;
loop();
}else{
}
}
}
for($i=0;$i<30;$++){
$x=0;
loop();
}
I'm sorry, I removed all the comments, they were annoying.
Move the declaration of $x outside of the for loop and replace your label/goto combination with a break, like so...
$x=0;
for($i=0;$i<30;$++) //print 30 articles
{
foreach($feed->get_items($x,1) as $item)
{
// create a unique id for the article of the feed
if($id==$dbid)
{
//if this id exists in the db,take the next article of the same feed which is not in the db
$x++;
continue;
}
else
{
//print the original article you grabbed
}
} // end of foreach
}//end of for
Agree with unset - using break will break if loop and keep iterating through for loop