PHP loop array implementation method, PHP loop array_PHP tutorial

PHP loop array implementation method, PHP loop array

Simply use foreach for list each while to traverse the array, including ordinary one-dimensional array and two-dimensional array traversal methods, The following describes how to use each function in detail.

<ol class="dp-c">
<li class="alt"><span class="vars">$foreach = <span class="keyword">array(1,2,3); </span></span></li>
<li><span class="vars">$array2 = <span class="keyword">array(<span class="keyword">array(<span class="string">'aa'=>33,<span class="string">'bb'=>22,<span class="string">'www.phpfensi.com'=>11),<span class="keyword">array(<span class="string">'dd'=>44,<span class="string">'ee'=>55,<span class="string">'ff'=>66)); </span></span></span></span></span></span></span></span></span></span></li>
</ol>

Use for foreach to traverse one-dimensional data:

<ol class="dp-c">
<li class="alt"><span class="keyword">for( <span class="vars">$i=0;<span class="vars">$i<<span class="func">count(<span class="vars">$foreach);<span class="vars">$i++) </span></span></span></span></span></span></li>
<li>{ </li>
<li class="alt"> <span class="func">echo <span class="string">'foreach['.<span class="vars">$i.<span class="string">']='.<span class="vars">$foreach[<span class="vars">$i].<span class="string">'<br>'; </span></span></span></span></span></span></span></li>
<li>} </li>
<li class="alt">/* </li>
<li><span class="comment">//foreach[0]=1 </span></li>
<li class="alt"><span class="comment">//foreach[1]=2 </span></li>
<li><span class="comment">//foreach[2]=3 </span></li>
</ol>

Look at using foreach to traverse:

<ol class="dp-c">
<li class="alt"><span class="keyword">foreach( <span class="vars">$foreach <span class="keyword">as <span class="vars">$v ) </span></span></span></span></li>
<li>{ </li>
<li class="alt"> <span class="func">echo <span class="string">'foreach='.<span class="vars">$v.<span class="string">'<br>'; </span></span></span></span></li>
<li>} </li>
<li class="alt"><span class="comment">//foreach=1 </span></li>
<li><span class="comment">//foreach=2 </span></li>
<li class="alt"><span class="comment">//foreach=3 </span></li>
</ol>

The above are used to traverse one-dimensional data. Let’s look at the two-dimensional array:

<ol class="dp-c">
<li class="alt"><span class="keyword">foreach(<span class="vars">$array2 <span class="keyword">as <span class="vars">$key=><span class="vars">$value) </span></span></span></span></span></li>
<li>{ </li>
<li class="alt"> <span class="keyword">foreach(<span class="vars">$value <span class="keyword">as <span class="vars">$k=><span class="vars">$v) </span></span></span></span></span></li>
<li> { </li>
<li class="alt">  <span class="func">echo <span class="string">'$arr['.<span class="vars">$key.<span class="string">']['.<span class="vars">$k.<span class="string">']='.<span class="vars">$v; </span></span></span></span></span></span></span></li>
<li> } </li>
<li class="alt"> <span class="func">echo <span class="string">"<br>"; </span></span></li>
<li>} </li>
</ol>

Look at the list each:

The

each() function generates an array consisting of the key name and key value of the element pointed to by the current internal pointer of the array, and moves the internal pointer forward.

The returned array includes four elements: key names 0, 1, key and value. Cells 0 and key contain the key names of the array cells, and 1 and value contain the data.

If the internal pointer exceeds the range of the array, this function will return false.

Syntax: each(array) parameter description

array required, specifies the array to be used.

list function

The list() function assigns values ​​to a set of variables using elements in the array.

Note that, similar to array(), list() is actually a language construct, not a function.

Syntax: list(var1,var2...) Parameter Description

var1 is required, the first variable that needs to be assigned a value.

var2 is optional and can have multiple variables.

Tips and Notes:

Note: This function is only used for numerically indexed arrays, and it is assumed that the numerical index starts from 0.

<ol class="dp-c">
<li class="alt"><span class="vars">$colors = <span class="keyword">array(<span class="string">'red',<span class="string">'blue',<span class="string">'green',<span class="string">'yellow');  </span></span></span></span></span></span></li>
<li><span class="keyword">while(list(<span class="vars">$key,<span class="vars">$val) = each(<span class="vars">$colors)) {  </span></span></span></span></li>
<li class="alt">    <span class="func">echo <span class="string">"other list of $val.<br />";  </span></span></li>
<li>} </li>
<li class="alt"><span class="comment">//other list of red. </span></li>
<li><span class="comment">//other list of blue. </span></li>
<li class="alt"><span class="comment">//other list of green. </span></li>
<li><span class="comment">//other list of yellow. </span></li>
</ol>

for statement:

If you have determined the number of times a block of code will be repeated, you can use a for statement.

Grammar:

<ol class="dp-c">
<li class="alt"><span class="keyword">for (initialization; condition; increment) </span></li>
<li>{ </li>
<li class="alt">  code to be executed; </li>
<li>} </li>
</ol>

Note: The for statement has three parameters. The first parameter initializes the variable, the second parameter saves the condition, and the third parameter contains the increment required to execute the loop. If the initialization or increment parameter includes multiple variables, They need to be separated by commas, and the condition must evaluate to true or false.

The foreach statement is used to loop through the array.

Every time the loop is performed, the value of the current array element will be assigned to the value variable (the array pointer will move one by one) - and so on.

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