Start foreach loop on associative array at the second element - php

Question

I have associative array such as:
$myArray = array(
'key1' => 'val 1',
'key2' => 'val 2'
...
);
I do not know the key values up front but want to start looping from the second element. In the example above, that would be from key2 onwards.
I tried
foreach(next(myArray) as $el) {
}
but that didnt work.
Alternatives may be array_slice but that seems messy. Am i missing something obvious?

Answer 1

There really is no "one true way" of doing this. So I'll take it as a benchmark as to where you should go.
All information is based on this array.
$array = array(
1 => 'First',
2 => 'Second',
3 => 'Third',
4 => 'Fourth',
5 => 'Fifth'
);
The array_slice() option. You said you thought this option was overkill, but it seems to me to be the shortest on code.
foreach (array_slice($array, 1) as $key => $val)
{
echo $key . ' ' . $val . PHP_EOL;
}
Doing this 1000 times takes 0.015888 seconds.
There is the array functions that handle the pointer, such as ...
current() - Return the current element in an array.
end() - Set the internal pointer of an array to its last element.
prev() - Rewind the internal array pointer.
reset() - Set the internal pointer of an array to its first element.
each() - Return the current key and value pair from an array and advance the array cursor.
Please note that the each() function has been deprecated as of PHP 7.2, and will be removed in PHP 8.
These functions give you the fastest solution possible, over 1000 iterations.
reset($array);
while (next($array) !== FALSE)
{
echo key($array) . ' ' . current($array) . PHP_EOL;
}
Doing this 1000 times, takes 0.014807 seconds.
Set a variable option.
$first = FALSE;
foreach ($array as $key => $val)
{
if ($first != TRUE)
{
$first = TRUE;
continue;
}
echo $key . ' ' . $val . PHP_EOL;
}
Doing this 1000 times takes 0.01635 seconds.
I rejected the array_shift options because it edits your array and you've never said that was acceptable.

Answer 2

This depends on whether you want to do this just once or many times, and on whether you still need the original array later on.
"First" pattern
$first = true;
foreach ($array as $key=>value) {
if($first) {
$first = false;
continue;
}
// ... more code ...
}
I personally use this solution quite often because it's really straight-forward, everybody gets this. Also, there is no performance hit of creating a new array and you can still operate on the original array after the loop.
However, if you have a couple of loops like this, it kind of starts looking a little unclean, because you need 5 extra lines of code per loop.
array_shift
array_shift($array);
foreach ($array as $key=>value) {
// .... more code ....
}
array_shift is a function tailored to this special case of not wanting the first element. Essentially it's a Perl-ish way of saying $array = array_slice($array, 1) which might not be completely obvious, especially since it modifies the original array.
So, you might want to make a copy of the original array and shift it, if you need both the shifted array multiple times and also the original array later on.
array_slice
And, of course, there is array_slice itself. I don't see anything wrong with array_slice if you want the original array to remain unchanged and you need the sliced array multiple times. However, if you're positive that you always want to slice just one element off, you might as well use the shorthand array_shift (and make a copy before if needed).

Answer 3

You can go with the obvious way:
$flag = false;
foreach($myArray as $el) {
if($flag) {
// do what you want
}
$flag = true;
}

Answer 4

Just another way of flexible iteration:
reset($myArray); // set array pointer to the first element
next($myArray); // skip first element
while (key($myArray) !== null) {
// do something with current($myArray)
next($myArray);
}
As far as I know foreach is just a kind of shortcut for this construction.
From Zend PHP 5 Certication study guide:
As you can see, using this set of functions [reset, next, key,
current, ...] requires quite a bit of work; to be fair, there are some
situations where they offer the only reasonable way of iterating
through an array, particularly if you need to skip back-and-forth
between its elements. If, however, all you need to do is iterate
through the entire array from start to finish, PHP provides a handy
shortcut in the form of the foreach() construct.

Answer 5

If your array was 0 based, it would be if($key>=1), but as your array starts at key 1, then this should work.
foreach ($array as $key=>$value){if($key>=2){
do stuff
}}

Answer 6

You could try:
$temp = array_shift($arr);
foreach($arr as $val) {
// do something
}
array_unshift($arr, $temp);

Answer 7

reset($myArray);
next($myArray);
while ($element = each($myArray))
{
//$element['key'] and $element['value'] can be used
}

Answer 8

My fairly simple solution when this issue pops up. It has the nice advantage of being easily being modified to be able to skip more than just the first element if you want it to.
$doomcounter = 0;
foreach ($doomsdayDevice as $timer){ if($doomcounter == 0){$doomcounter++; continue;}
// fun code goes here
}