连续遍历数组

Question

I'm trying to work out how to continuously loop through an array, but apparently using foreach doesn't work as it works on a copy of the array or something along those lines.

I tried:

$amount = count($stuff);
$last_key = $amount - 1;

foreach ($stuff as $key => $val) {

    // Do stuff

    if ($key == $last_key) {
        // Reset array cursor so we can loop through it again...
        reset($stuff);
    }

}

But obviously that didn't work. What are my choices here?

Answer 1

You can accomplish this with a while loop:

while (list($key, $value) = each($stuff)) {
    // code
    if ($key == $last_key) {
        reset($stuff); 
    }
}

Answer 2

This loop will never stop:

while(true) {
    // do something
}

If necessary, you can break your loop like this:

while(true) {
    // do something
    if($arbitraryBreakCondition === true) {
        break;
    }
}

Answer 3

An easy way is to combine an ArrayIterator with an InfiniteIterator .

$infinite = new InfiniteIterator(new ArrayIterator($array));
foreach ($infinite as $key => $val) {
    // ...
}

Answer 4

You could use a for loop and just set a condition that's always going to be true - for example:

$amount = count($stuff);
$last_key = $amount - 1;

for($key=0;1;$key++)
{
    // Do stuff
    echo $stuff[$key];

    if ($key == $last_key) {
        // Reset array cursor so we can loop through it again...
        $key= -1;
    }


}

Obviously, as other's have pointed out - make sure you've got something to stop the looping before you run that!

Answer 5

Here's one using reset() and next():

$total_count = 12;
$items = array(1, 2, 3, 4);

$value = reset($items);
echo $value;
for ($j = 1; $j < $total_count; $j++) {
    $value = ($next = next($items)) ? $next : reset($items);
    echo ", $value";
};

Output:

1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4

I was rather surprised to find no such native function. This is a building block for a Cartesian product.

Answer 6

Using a function and return false in a while loop:

function stuff($stuff){
   $amount = count($stuff);
   $last_key = $amount - 1;

   foreach ($stuff as $key => $val) {

       // Do stuff

       if ($key == $last_key) {
           // Reset array cursor so we can loop through it again...
           return false;
       }

   }
}

while(stuff($stuff)===FALSE){
    //say hello
}