拍拍尘土

foreach()有两种用法：1： foreach(array_name as $value) { statement; }这里的array_name是你要遍历的数组名，每次循环中，array_name数组的当前元素的值被赋给$value,并且数组内部的下标向下移一步，也就是下次循环回得到下一个元素。2：foreach(array_name as $key => $value) { statement; } 这里跟第一种方法的区别就是多了个$key,也就是除了把当前元素的值赋给$value外，当前元素的键值也会在每次循环中被赋给变量$key。键值可以是下标值，也可以是字符串。比如book[0]=1中的“0”，book[id]="001"中的“id”.

示范用法的更多例子：

<?php
/*-------------------------------------------------------------------------*/
/* foreach example 1: value only */
echo "foreach example 1: value only ".'<br />';

$a = array(1, 2, 3, 17);

foreach ($a as $v) {
      echo "Current value of "$a: $v".'<br />';
}

/*-------------------------------------------------------------------------*/
/* foreach example 2: value (with key printed for illustration) */
echo '<br />'.'<br />'."foreach example 2: value (with key printed for illustration) ".'<br />';

$a = array(1, 2, 3, 17);

$i = 0; /* for illustrative purposes only */

foreach ($a as $v) {
        echo ""$a[$i] => $v".'<br />';
        $i++;
}

/*-------------------------------------------------------------------------*/
/* foreach example 3: key and value */
echo '<br />'.'<br />'."foreach example 3: key and value ".'<br />';

$a = array(
        "one" => 1,
        "two" => 2,
        "three" => 3,
        "seventeen" => 17
);

foreach ($a as $k => $v) {
        echo ""$a[$k] => $v".'<br />';
}

/*-------------------------------------------------------------------------*/
/* foreach example 4: multi-dimensional arrays */
echo '<br />'.'<br />'."foreach example 4: multi-dimensional arrays ".'<br />';

$a = array();
$a[0][0] = "a";
$a[0][1] = "b";
$a[1][0] = "y";
$a[1][1] = "z";

foreach ($a as $v1) {
        foreach ($v1 as $v2) {
               echo "$v2"n";
        }
}

/*-------------------------------------------------------------------------*/
/* foreach example 5: dynamic arrays */
echo '<br />'.'<br />'."foreach example 5: dynamic arrays ".'<br />';

foreach (array(1, 2, 3, 4, 5) as $v) {
        echo "$v"n";
}
?>


结果如下:

foreach example 1: value only
Current value of $a: 1
Current value of $a: 2
Current value of $a: 3
Current value of $a: 17


foreach example 2: value (with key printed for illustration)
$a[0] => 1
$a[1] => 2
$a[2] => 3
$a[3] => 17


foreach example 3: key and value
$a[one] => 1
$a[two] => 2
$a[three] => 3
$a[seventeen] => 17


foreach example 4: multi-dimensional arrays
a b y z

foreach example 5: dynamic arrays
1 2 3 4 5

 

 

/* foreach example 3: key and value */
echo '<br />'.'<br />'."foreach example 3: key and value ".'<br />';

$messageNav['首页'] =ROOT_PATH;

$messageNav['人才交流'] ="#"

$messageNav['动态专栏'] ="hragent/cn/"

<?php $i = 0;foreach ($messageNav as $key=>$value):?>

<?php if ($i != count($messageNav) - 1):?>
<a href="<?=$value?>"><?=$key?></a>&gt;
<?php else:?>

<a href="<?=$value?>" class="onlink"><?=$key?></a>
<?php endif;?>
<?php $i++;endforeach;?>

print out result:首页>人才交流>动态专栏