PHP Loop Array problem

$a = Array (' Abe ', ' Ben ', ' cam '); When a foreach iterates through an array, it is actually a copy of the traversed array and points the pointer to the beginning of the copy before it starts, and, according to the cow mechanism, re-copies the cell in the array, foreach ($a as $k =>& $n) {    $n = $n; Equivalent to the following//$n =& $a [' 0 '];//$n =& $a [' 1 '];//$n =& $a [' 2 '];} Unset ($n); Good habits print_r ($a);  foreach ($a as $k = $n) {//Notice NO reference here!//k=0     & $a [2] = n = Abe   [' Abe ', ' Ben ', ' Abe ']//k=1     & $a [2] n=ben       [' Abe ', ' Ben ', ' Ben ']//k=2     & $a [2] n=cam       [' Abe ', ' Ben ', ' Ben ']   echo ' $n \ n ';} Print_r ($a);

　　

$data = [' A ', ' B ', ' C ', ' d '];foreach ($data as $key = = $val) {$val = & $data [$key];} echo "<pre>";p Rint_r ($data);

　　

1,php memory usage Policy at variable assignment: Copy on Write, COW, when assigning a variable value to another variable using an assignment method, because the values of the two variables are the same, the same memory is common, and when one of the variable values changes, will be re-applied to the variable value of memory, has achieved the purpose of saving memory;
When 2,foreach iterates through an array, it is actually a copy of the traversed array, and the pointer points to the beginning of the copy before it begins to traverse;
3, the position of the pointer will also be copied when the copy occurs.

PHP Loop Array problem