在PHP foreach中重用collection var作为迭代var

Question

I have a coworker that I noticed was using his foreachs in the following fashion:

foreach ($var as $var) {
    // do stuff here
}

I have tested the code above and it works correctly to my surprise. Would the PHP gurus like to hop in and tell me why this is wrong? It feels very wrong.

Answer 1

Because it changes the value of $var. After the foreach() it's no longer an array but is set to the last value in the array.

$var = array('apple', 'orange');
foreach ($var as $var) {
    echo $var."<br/>";
}
echo $var; //orange

If you don't want to change the variable's value, it'll need to be a different variable name:

$var = array('apple', 'orange');
foreach ($var as $fruit) {
    echo $fruit."<br/>";
}
echo $var; //array

As @UselessIntern pointed out, it's fine if you're not going to use the variable after looping through it, but it's definitely not encouraged because it can lead to confusion.

As @PLB pointed out, it iterates over a copy of the $var not $var itself. So every iteration the value of $var is changing, but it doesn't break the loop because it's looping over the copy that was created.