PHP变量的指针,在变量前加&号

时间：2006-09-16 18:02:48   类别：技术   访问：3354

以下是手册中关于PHP变量的指针的例子,理解一下.
注意其中几行加粗的,变量的变化.

In response to the example by mdiricks.

Extending the example given by mdiricks, the following code provides an explains the concept of re-referencing that is involved in making a call to function foo with the prototype foo(& var):

<!-- C re-referenced -->
<?

$a = 'eh';
$b = & $a; // $b == 'eh'
$c = & $b; // $c == 'eh'
$d = 'meh';

echo "\$a = $a\n"; //$a = eh
echo "\$b = $b\n"; //$b = eh
echo "\$c = $c\n"; //$c = eh
echo "\$d = $d\n"; //$d = meh

$c = & $d ;// $c == 'meh'
echo "\n";

echo "\$a = $a\n"; //$a = eh
echo "\$b = $b\n"; //$b = eh
echo "\$c = $c\n"; //$c = meh
echo "\$d = $d\n"; //$d = meh

?>

<!-- Value of c changed -->
<?

$a = 'eh';
$b = & $a;// $b == 'eh'
$c = & $b;// $c == 'eh'
$d = 'meh';

echo "\$a = $a\n"; //$a = eh
echo "\$b = $b\n"; //$b = eh
echo "\$c = $c\n"; //$c = eh
echo "\$d = $d\n"; //$d = meh

$c = 'meh' ;// $c == 'meh'. And also, $a = $b == 'meh'
echo "\n";

echo "\$a = $a\n"; //$a = meh
echo "\$b = $b\n"; //$b = meh
echo "\$c = $c\n"; //$c = meh
echo "\$d = $d\n"; //$d = meh

?>

This results in the following o/p:
<!-- C re-referenced -->
$a = eh
$b = eh
$c = eh
$d = meh

$a = eh
$b = eh
$c = meh
$d = meh

<!-- Value of c changed -->
$a = eh
$b = eh
$c = eh
$d = meh

$a = meh
$b = meh
$c = meh
$d = meh

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