1: Why not use a simple for statement? Assuming you're using a real array and not an Iterator you could easily check whether the counter variable is 0 or one less than the whole number of elements. In my opinion this is the most clean and understandable solution...
$array = array( ... );
$count = count( $array );
for ( $i = 0; $i < $count; $i++ )
{
$current = $array[ $i ];
if ( $i == 0 )
{
// process first element
}
if ( $i == $count - 1 )
{
// process last element
}
}
2: You should consider using Nested Sets to store your tree structure. Additionally you can improve the whole thing by using recursive functions.
If you prefer a solution that does not require the initialization of the counter outside the loop, I propose comparing the current iteration key against the function that tells you the last / first key of the array.
This becomes somewhat more efficient (and more readable) with the upcoming PHP 7.3.
foreach($array as $key => $element) {
if ($key === array_key_first($array))
echo 'FIRST ELEMENT!';
if ($key === array_key_last($array))
echo 'LAST ELEMENT!';
}
foreach($array as $key => $element) {
reset($array);
if ($key === key($array))
echo 'FIRST ELEMENT!';
end($array);
if ($key === key($array))
echo 'LAST ELEMENT!';
}
A more simplified version of the above and presuming you're not using custom indexes...
$len = count($array);
foreach ($array as $index => $item) {
if ($index == 0) {
// first
} else if ($index == $len - 1) {
// last
}
}
Version 2 - Because I have come to loathe using the else unless necessary.
$len = count($array);
foreach ($array as $index => $item) {
if ($index == 0) {
// first
// do something
continue;
}
if ($index == $len - 1) {
// last
// do something
continue;
}
}
Try this:
function children( &$parents, $parent, $selected ){
if ($parents[$parent]){
$list = '<ul>';
$counter = count($parents[$parent]);
$class = array('first');
foreach ($parents[$parent] as $child){
if ($child['id'] == $selected) $class[] = 'active';
if (!--$counter) $class[] = 'last';
$list .= '<li class="' . implode(' ', $class) . '"><div><a href="]?id=' . $child['id'] . '" alt="' . $child['name'] . '">' . $child['name'] . '</a></div></li>';
$class = array();
$list .= children($parents, $child['id'], $selected);
}
$list .= '</ul>';
return $list;
}
}
$output .= children( $parents, 0, $p_industry_id);
For SQL query generating scripts, or anything that does a different action for the first or last elements, it is much faster (almost twice as fast) to avoid using unneccessary variable checks.
The current accepted solution uses a loop and a check within the loop that will be made every_single_iteration, the correct (fast) way to do this is the following :
$numItems = count($arr);
$i=0;
$firstitem=$arr[0];
$i++;
while($i<$numItems-1){
$some_item=$arr[$i];
$i++;
}
$last_item=$arr[$i];
$i++;
A little homemade benchmark showed the following:
test1: 100000 runs of model morg
time: 1869.3430423737 milliseconds
test2: 100000 runs of model if last
time: 3235.6359958649 milliseconds
And it's thus quite clear that the check costs a lot, and of course it gets even worse the more variable checks you add ;)
You could remove the first and last elements off the array and process them separately.
Like this:
<?php
$array = something();
$first = array_shift($array);
$last = array_pop($array);
// do something with $first
foreach ($array as $item) {
// do something with $item
}
// do something with $last
?>
Removing all the formatting to CSS instead of inline tags would improve your code and speed up load time.
You could also avoid mixing HTML with php logic whenever possible.
Your page could be made a lot more readable and maintainable by separating things like this:
<?php
function create_menu($params) {
//retrieve menu items
//get collection
$collection = get('xxcollection') ;
foreach($collection as $c) show_collection($c);
}
function show_subcat($val) {
?>
<div class="sub_node" style="display:none">
<img src="../images/dtree/join.gif" align="absmiddle" style="padding-left:2px;" />
<a id="'.$val['xsubcatid'].'" href="javascript:void(0)" onclick="getProduct(this , event)" class="sub_node_links" >
<?php echo $val['xsubcatname']; ?>
</a>
</div>
<?php
}
function show_cat($item) {
?>
<div class="node" >
<img src="../images/dtree/plus.gif" align="absmiddle" class="node_item" id="plus" />
<img src="../images/dtree/folder.gif" align="absmiddle" id="folder">
<?php echo $item['xcatname']; ?>
<?php
$subcat = get_where('xxsubcategory' , array('xcatid'=>$item['xcatid'])) ;
foreach($subcat as $val) show_subcat($val);
?>
</div>
<?php
}
function show_collection($c) {
?>
<div class="parent" style="direction:rtl">
<img src="../images/dtree/minus.gif" align="absmiddle" class="parent_item" id="minus" />
<img src="../images/dtree/base.gif" align="absmiddle" id="base">
<?php echo $c['xcollectionname']; ?>
<?php
//get categories
$cat = get_where('xxcategory' , array('xcollectionid'=>$c['xcollectionid']));
foreach($cat as $item) show_cat($item);
?>
</div>
<?php
}
?>
Simply this works!
// Set the array pointer to the last key
end($array);
// Store the last key
$lastkey = key($array);
foreach($array as $key => $element) {
....do array stuff
if ($lastkey === key($array))
echo 'THE LAST ELEMENT! '.$array[$lastkey];
}
Thank you @billynoah for your sorting out the end issue.
Best answer:
$arr = array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
foreach ($arr as $a) {
// This is the line that does the checking
if (!each($arr)) echo "End!\n";
echo $a."\n";
}
Not sure if it still necessary. But the following solution should work with iterators and does not require count.
<?php
foreach_first_last(array(), function ($key, $value, $step, $first, $last) {
echo intval($first), ' ', intval($last), ' ', $step, ' ', $value, PHP_EOL;
});
foreach_first_last(array('aa'), function ($key, $value, $step, $first, $last) {
echo intval($first), ' ', intval($last), ' ', $step, ' ', $value, PHP_EOL;
});
echo PHP_EOL;
foreach_first_last(array('aa', 'bb', 'cc'), function ($key, $value, $step, $first, $last) {
echo intval($first), ' ', intval($last), ' ', $step, ' ', $value, PHP_EOL;
});
echo PHP_EOL;
function foreach_first_last($array, $cb)
{
$next = false;
$current = false;
reset($array);
for ($step = 0; true; ++$step) {
$current = $next;
$next = each($array);
$last = ($next === false || $next === null);
if ($step > 0) {
$first = $step == 1;
list ($key, $value) = $current;
if (call_user_func($cb, $key, $value, $step, $first, $last) === false) {
break;
}
}
if ($last) {
break;
}
}
}
To find the last item, I find this piece of code works every time:
foreach( $items as $item ) {
if( !next( $items ) ) {
echo 'Last Item';
}
}
The most efficient answer from @morg, unlike foreach, only works for proper arrays, not hash map objects. This answer avoids the overhead of a conditional statement for every iteration of the loop, as in most of these answers (including the accepted answer) by specifically handling the first and last element, and looping over the middle elements.
The array_keys function can be used to make the efficient answer work like foreach:
$keys = array_keys($arr);
$numItems = count($keys);
$i=0;
$firstItem=$arr[$keys[0]];
# Special handling of the first item goes here
$i++;
while($i<$numItems-1){
$item=$arr[$keys[$i]];
# Handling of regular items
$i++;
}
$lastItem=$arr[$keys[$i]];
# Special handling of the last item goes here
$i++;
I haven't done benchmarking on this, but no logic has been added to the loop, which is were the biggest hit to performance happens, so I'd suspect that the benchmarks provided with the efficient answer are pretty close.
If you wanted to functionalize this kind of thing, I've taken a swing at such an iterateList function here. Although, you might want to benchmark the gist code if you're super concerned about efficiency. I'm not sure how much overhead all the function invocation introduces.
Using reset($array) and end($array)
<?php
$arrays = [1,2,3,4,5];
$first = reset($arrays);
$last = end($arrays);
foreach( $arrays as $array )
{
if ( $first == $array )
{
echo "<li>{$array} first</li>";
}
else if ( $last == $array )
{
echo "<li>{$array} last</li>";
}
else
{
echo "<li>{$array}</li>";
}
}
I came across this thread when I have the same problem. I only need to get the first element then I re-analyze my code until this came up to my mind.
$firstElement = true;
foreach ($reportData->result() as $row)
{
if($firstElement) { echo "first element"; $firstElement=false; }
// Other lines of codes here
}
The above codes are great and complete but if you only need just the first element then you may try this code.
You can use an anonymous function, too:
$indexOfLastElement = count($array) - 1;
array_walk($array, function($element, $index) use ($indexOfLastElement) {
// do something
if (0 === $index) {
// first element‘s treatment
}
if ($indexOfLastElement === $index) {
// last not least
}
});
Three more things should be mentioned:
array_values first.$element you have to pass it by reference (&$element).$indexOfLastElement inside the use construct, again by reference if needed.An attempt to find the first would be:
$first = true;
foreach ( $obj as $value )
{
if ( $first )
{
// do something
$first = false; //in order not to get into the if statement for the next loops
}
else
{
// do something else for all loops except the first
}
}
foreach ($arquivos as $key => $item) {
reset($arquivos);
// FIRST AHEAD
if ($key === key($arquivos) || $key !== end(array_keys($arquivos)))
$pdf->cat(null, null, $key);
// LAST
if ($key === end(array_keys($arquivos))) {
$pdf->cat(null, null, $key)
->execute();
}
}
Using a Boolean variable is still the most reliable, even if you want to check the first appearance of a $value (I found it more useful in my situation and in many situations), such like this:
$is_first = true;
foreach( $array as $value ) {
switch ( $value ) {
case 'match':
echo 'appeared';
if ( $is_first ) {
echo 'first appearance';
$is_first = false;
}
break;
}
}
if( !next( $array ) ) {
echo 'last value';
}
}
Then how about !next( $array ) to find the last $value which will return true if there's no next() value to iterate.
And I prefer to use a for loop instead of foreach if I were going to use a counter, like this:
$len = count( $array );
for ( $i = 0; $i < $len; $i++ ) {
$value = $array[$i];
if ($i === 0) {
// first
} elseif ( $i === $len - 1 ) {
// last
}
// …
$i++;
}
With Keys and Values this works as well:
foreach ($array as $key => $value) {
if ($value === end($array)) {
echo "LAST ELEMENT!";
}
}
You can use the counter and array length.
$array = array(1,2,3,4);
$i = 0;
$len = count($array);
foreach ($array as $item) {
if ($i === 0) {
// first
} else if ($i === $len - 1) {
// last
}
// …
$i++;
}
Source: Stackoverflow.com