03-Mar-2014 in Software Development #PHP

Using list() with foreach() in PHP

Continuing my showcasing of all of the awesomeness in PHP 5.5 that I am discovering since my upgrade from 5.3, let's discuss using the the list() function inside of a foreach() block.

Have you ever had a situation where you are looping through a multi-dimensional array and the array is non-associative? If so, you probably have some code that looks like this:

$items = array(
    array('var1', 'var2', 'var3'),
    array('var1', 'var2', 'var3'),
    array('var1', 'var2', 'var3'),
    array('var1', 'var2', 'var3'),
    array('var1', 'var2', 'var3'),
);
foreach ($items as $item)
{
list($var1, $var2, $var3) = $item;
if ($var1 == $var2)
{
echo $var3;
}
}

Or even worse, you're not even using the list() function:

foreach ($items as $item)
{
    $var1 = $item[0];
    $var2 = $item[1];
    $var3 = $item[3];
if ($var1 == $var2)
{
echo $var3;
}
}

Or worse than that, lacking any sort of variable mapping / meaningful references to the variables:

foreach ($items as $item)
{
    if ($item[0] == $item[1])
    {
        echo $item[2];
    }
}

NO LONGER! as now you can leverage the assignment power of list() right inside of your foreach() statement:

foreach ($items as list($var1, $var2, $var3))
{
    if ($var1 == $var2)
    {
        echo $var3;
    }
}

I haven't run any benchmarks to see if this is any faster or slower than using list() inside of the block itself instead of in the statement, but to me it's worth a small bit of overhead for the cleanliness of the code when dealing with a small number of arguments.

What's your preferred method? Comment below!