Introduction to two methods of using foreach in php-PHP Tutorial-php.cn

Introduction to two methods of using foreach in php

伊谢尔伦

Release： 2023-03-11 06:54:02

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Use foreach in php to operate array code

foreach() has two uses:

foreach(array_name as $value) 
{ 
statement; 
}

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The array_name here is you The name of the array to be traversed. In each loop, the value of the current element of the array_name array is assigned to $value, and the subscript inside the array moves down one step, that is, the next element is obtained in the next loop.

foreach(array_name as $key => $value) 
{ 
statement; 
}

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The difference between this and the first method is that there is an extra $key, that is, in addition to assigning the value of the current element to $value, the key value of the current element will also be assigned in each loop. Give the variable $key. The key value can be a subscript value or a string. For example, "0" in book[0]=1, "id" in book[id]="001".
Program Example 1:

<?php 
/*-------------------------------------------------------------------------*/ 
/* foreach example 1: value only */ 
echo "foreach example 1: value only ".&#39;<br />&#39;; 
$a = array(1, 2, 3, 17); 
foreach ($a as $v) { 
echo "
Current
 value of ".$a.":". $v."<br />"; 
} 
?>

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// Running results
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) */ 
echo &#39;<br />&#39;.&#39;<br />&#39;."foreach example 2: value (with key printed for illustration) ".&#39;<br />&#39;; 
$a = array(1, 2, 3, 17); 
$i = 0; /* for illustrative purposes only */ 
foreach ($a as $v) { 
echo ""$a[$i] => $v".&#39;<br />&#39;; 
$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

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/*-------------------------------------------------------------------------*/ 
/* foreach example 3: key and value */ 
echo &#39;<br />&#39;.&#39;<br />&#39;."foreach example 3: key and value ".&#39;<br />&#39;; 
$a = array( 
"one" => 1, 
"two" => 2, 
"three" => 3, 
"seventeen" => 17 
); 
foreach ($a as $k => $v) { 
echo ""$a[$k] => $v".&#39;<br />&#39;; 
} 
// 程序运行结果 
foreach example 3: key and value 
$a[one] => 1 
$a[two] => 2 
$a[three] => 3 
$a[seventeen] => 17

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/*-------------------------------------------------------------------------*/ 
/* foreach example 4: multi-dimensional arrays */ 
echo &#39;<br />&#39;.&#39;<br />&#39;."foreach example 4: multi-dimensional arrays ".&#39;<br />&#39;; 
$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

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/*-------------------------------------------------------------------------*/ 
/* foreach example 5: dynamic arrays */ 
echo &#39;<br />&#39;.&#39;<br />&#39;."foreach example 5: dynamic arrays ".&#39;<br />&#39;; 
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

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can also be used like this:

$messageNav[&#39;首页&#39;] =ROOT_PATH; 
$messageNav[&#39;人才交流&#39;] ="#" 
$messageNav[&#39;动态专栏&#39;] ="hragent/cn/" 
<?php $i = 0;foreach ($messageNav as $key=>$value):?> 
<?php if ($i != count($messageNav) - 1):?> 
<a href="<?=$value?>"><?=$key?></a>> 
<?php else:?> 
<a href="<?=$value?>" class="onlink"><?=$key?></a> 
<?php endif;?> 
<?php $i++;endforeach;?>

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