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Multiple index variables in PHP foreach loop

Posted by: admin November 30, 2017 Leave a comment

Questions:

Is it possible to have a foreach loop in PHP with multiple “index” variables, akin to the following (which doesn’t use correct syntax)?

foreach ($courses as $course, $sections as $section)

If not, is there a good way to achieve the same result?

Answers:

to achieve just that result you could do

foreach (array_combine($courses, $sections) as $course => $section)

but that only works for two arrays

Questions:
Answers:

If both the arrays are of the same size you can use a for loop as:

for($i=0, $count = count($courses);$i<$count;$i++) {
 $course  = $courses[$i];
 $section = $sections[$i];
}

Questions:
Answers:

You would need to use nested loops like this:

foreach($courses as $course)
{
    foreach($sections as $section)
    {
    }
}

Of course, this will loop over every section for every course.

If you want to look at each pair, you are better off using either objects that contain the course/section pairs and looping over those, or making sure the indexes are the same and doing:

foreach($courses as $key => $course)
{
    $section = $sections[$key];
}

Questions:
Answers:

TRY –

1)

<?php
$FirstArray = array('a', 'b', 'c', 'd');
$SecondArray = array('1', '2', '3', '4');

foreach($FirstArray as $index => $value) {
    echo $FirstArray[$index].$SecondArray[$index];
    echo "<br/>";
}
?>

or 2)

<?php
$FirstArray = array('a', 'b', 'c', 'd');
$SecondArray = array('1', '2', '3', '4');

for ($index = 0 ; $index < count($FirstArray); $index ++) {
  echo $FirstArray[$index] . $SecondArray[$index];
  echo "<br/>";
}
?>

Questions:
Answers:

No, because those arrays may have other number of items.

You must explicitely write something like that:

for ($i = 0; $i < count($courses) && $i < count($sections); ++$i) {
    $course = $courses[$i];
    $section = $sections[$i];

    //here the code you wanted before
}

Questions:
Answers:

No, this is maybe one of the rare cases PHP’s array cursors are useful:

reset($sections);
foreach ($courses as $course)
{
 list($section) = each($sections);
}

Questions:
Answers:

What would that do, exactly? Are $courses and $sections just two separate arrays, and you want to perform the same function for the values in each? You could always do:

foreach(array_merge($courses, $sections) as $thing) { ... }

This makes all the usual assumptions about array_merge, of course.

Or is it that $sections comes from $course and you want to do something for each section in each course?

foreach($courses as $course) {
    foreach($sections as $section) {
        // Here ya go
    }
}

Questions:
Answers:

like this?

foreach($array as $b=>$c){

}