在这种情况下，我如何使用“foreach”代替“for”循环？

I want to make a loop to display each category and all sub-categories. I have this array:

$Allcategories = array(
  array(
    array("Category 1", 'category1'),
    array("Sub 1", 'sub1'),
    array("Sub 2", 'sub2'), 
    array("Sub 3", 'sub3') 
  ),
  array(
      array("Category 2", 'category2'),
      array("Sub 1", 'sub1'),
      array("Sub 2", 'sub2'), 
      array("Sub 3", 'sub3')
    )
);

I already made a 3-nest-for loop that works but I would like to simplify it with a foreach. Here is my for loop:

foreach ($Allcategories as $val_1)
{    
    echo "<a href='index.php?category=", $val_1[0][1], "'>", $val_1[0][0], "</a>";    
    foreach ($val_1 as $val_2)
    {    
        foreach ($val_2 as $val_3)
        {
            printf('<li><a href="index.php?category=%1$s">%1$s</a><br />', $val_3);
        }    
    }    
}

The problem is I'm getting this result:

Category 1

    -Category 1

    -category1

    -Sub 1

    -sub1

    -Sub 2

    -sub2

The inner loops shouldn't iterate over $Allcategories, but rather, over the values from the outer loops:

foreach ($Allcategories as $layerNum => $layer) {
    ...
    foreach ($layer as $rowNum => $row) {
        ...
        foreach ($row as $colNum => $category) {

Although you should write it as ruakh has shown, it might be useful to know that the problem with your code is that you're forgetting to reference $key3. It should be:

echo "<li><a href='index.php?category=".$Allcategories[$key1][$key2][$key3]
[1]."'>".$Allcategories[$key1][$key2][$key3][0]."</a><br />";

Edit: Or better yet, the whole thing:

foreach ($Allcategories as $val_1)
{

  echo "<a href='index.php?category=" . $val_1[0][1] . "'>" . $val_1[0][0] . "</a>";

  foreach ($val_1 as $val_2)
  {

    foreach ($val_2 as $val_3)
    {
      echo "<li><a href='index.php?category=" . $val_3[1] . "'>" . $val_3[0] . "</a><b></li>";
    }

  }

}

I've also taken the liberty or removing the <br /> and instead closed the <li> as I believe that's what you want?