php中用foreach来操作数组的代码_php技巧

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。 
 代码如下:

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". 
程序实例1： 
 代码如下:

/*-------------------------------------------------------------------------*/ 
/* foreach example 1: value only */ 
echo "foreach example 1: value only ".'
'; 
$a = array(1, 2, 3, 17); 
foreach ($a as $v) { 
echo "Current value of ".$a.":". $v."
"; 
} 
?> 
// 运行结果 
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 
 
2 
 代码如下:

/*-------------------------------------------------------------------------*/ 
/* foreach example 2: value (with key printed for illustration) */ 
echo '
'.'
'."foreach example 2: value (with key printed for illustration) ".'
'; 
$a = array(1, 2, 3, 17); 
$i = 0; /* for illustrative purposes only */ 
foreach ($a as $v) { 
echo ""$a[$i] => $v".'
'; 
$i++; 
} 
// 程序运行结果 
foreach example 2: value (with key printed for illustration) 
$a[0] => 1 
$a[1] => 2 
$a[2] => 3 
$a[3] => 17 
 
3 
 代码如下:

/*-------------------------------------------------------------------------*/ 
/* foreach example 3: key and value */ 
echo '
'.'
'."foreach example 3: key and value ".'
'; 
$a = array( 
"one" => 1, 
"two" => 2, 
"three" => 3, 
"seventeen" => 17 
); 
foreach ($a as $k => $v) { 
echo ""$a[$k] => $v".'
'; 
} 
// 程序运行结果 
foreach example 3: key and value 
$a[one] => 1 
$a[two] => 2 
$a[three] => 3 
$a[seventeen] => 17 
 
4 
 代码如下:

/*-------------------------------------------------------------------------*/ 
/* foreach example 4: multi-dimensional arrays */ 
echo '
'.'
'."foreach example 4: multi-dimensional arrays ".'
'; 
$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"; 
} 
} 
// 程序运行结果 
foreach example 4: multi-dimensional arrays 
a b y z 
 
5 
 代码如下:

/*-------------------------------------------------------------------------*/ 
/* foreach example 5: dynamic arrays */ 
echo '
'.'
'."foreach example 5: dynamic arrays ".'
'; 
foreach (array(1, 2, 3, 4, 5) as $v) { 
echo "$v"n"; 
} 
// 程序运行结果 
foreach example 5: dynamic arrays 
1 2 3 4 5 
 
也可以这么用： 
 代码如下:

$messageNav['首页'] =ROOT_PATH; 
$messageNav['人才交流'] ="#" 
$messageNav['动态专栏'] ="hragent/cn/" 
$value):?> 
 
">> 
 
" class="onlink">