Introduction to the usage of var_export and var_dump

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Introduction to the usage of var_export and var_dump_PHP tutorial

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Jul 13, 2016 pm 05:14 PM

dump export var one time under and introduce about us use usage

Now let’s introduce the usage of var_export and var_dump. Friends in need can refer to it.

var_export must return legal PHP code. In other words, the code returned by var_export can be directly assigned to a variable as PHP code. And this variable will get the same type of value as var_export

•However, when the variable type is resource, it cannot be copied simply. Therefore, when the variable of var_export is of resource type, var_export will return NULL

Example

The code is as follows

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代码如下

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$res = yblog_mspconfiginit("ratings");
var_dump($res);
var_export($res);结果:

resource(1) of type (yahoo_yblog)
NULL再比如:

$res = fopen('status.html', 'r');
var_dump($res);
var_export($res);结果:

resource(2) of type (stream)
NULL

$res = yblog_mspconfiginit("ratings");
var_dump($res);
var_export($res);Result:

resource(1) of type (yahoo_yblog)
NULL Another example:

代码如下

复制代码

//php var_export读写实例类
class user{
var $filepath;
function __()
{
$this->filepath = "d:/www.bKjia.c0m/group/";
}
function cache() {
$array = $this->db->select('select group_id,group_name from group','hashmap');
$fp = fopen ($this->filepath, 'w');
fputs($fp, '');
fclose($fp);
}

//使用实例方法

$g = new user();
if( intval( $_GET['iscreate']) )
{
$g->cache();
}
else
{
$g->getVar_export('vv');
}
//本站原创www.bKjia.c0m转载注明来源
?>

$res = fopen('status.html', 'r');
var_dump($res);
var_export($res);Result: resource(2) of type (stream)
NULL

Example

The code is as follows

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//php var_export read and write instance class
class user{
var $filepath;
function __()
{
$this->filepath = "d:/www.bKjia.c0m/group/";
}
function cache() {
$array = $this->db->select('select group_id,group_name from group','hashmap');
$fp = fopen ($this->filepath, 'w');
fputs($fp, '');
fclose($fp);
} function getVar_export($value) {
$array = require($this->filepath);
foreach ($array as $key => $v) {
if ($key==$value) {
$selected = ' current option';
} else {
$selected = '';
}
$html .= '';
}

return $html;
}
} //Use instance method $g = new user();
if( intval( $_GET['iscreate']) )
{
$g->cache();
}
else
{
$g->getVar_export('vv');
}
//This site’s original www.bKjia.c0m reprints indicate the source
?>

For more details, please check: http://www.bKjia.c0m/phper/21/02496253b66d66ca613a2f19ea40c22e.htm

var_dump function
var_dump　 (PHP 3 >= 3.0.5, PHP 4, PHP 5) 　

var_dump -- Print information about variables

void var_dump ( mixed expression [, mixed expression [, ...]] )

This function displays structural information about one or more expressions, including the type and value of the expression. Arrays will expand values recursively, showing their structure through indentation.

Tip: To prevent the program from outputting the results directly to the browser, you can use output-control functions to capture the output of this function and save them to a variable of type string, for example.

You can compare var_dump() and print_r().

Example

</tr>
</table>　<?php</p>
<p align="left">　$a = array (1, 2, array ("a", "b", "c"));<div style="display:none;">
<span id="url" itemprop="url">　var_dump ($a);</span>
<span id="indexUrl" itemprop="indexUrl"> /* Output: </span>
<span id="isOriginal" itemprop="isOriginal"> array(3) {</span>
<span id="isBasedOnUrl" itemprop="isBasedOnUrl">　[0]=>
<span id="genre" itemprop="genre">int(1)</span>
<span id="description" itemprop="description">　[1]=></span>
int(2)
　[2]=><div class="art_confoot">
</div> array(3) {
　[0]=>
 String(1) "a"
　[1]=>
 String(1) "b"
　[2]=>
 String(1) "c"
　}
　}
　*/
　$b = 3.1;
　$c = TRUE;
 var_dump($b,$c);
 /* Output: 
 float(3.1)
bool(true)
　*/
　?>

For more details, please check: http://www.bKjia.c0m/phper/php/43382.htm http://www.bkjia.com/PHPjc/628989.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/628989.htmlTechArticleLet’s introduce the usage of var_export and var_dump. Friends in need can refer to it. var_export must return legal php code, that is, the code returned by var_export,...

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The code is as follows

代码如下

复制代码

代码如下复制代码

</p>
<p>　　<?php</p>
<p>　　$a = array (1, 2, array ("a", "b", "c"));</p>
<p>　　var_dump ($a);</p>
<p>　　/* 输出：</p>
<p>　　array(3) {</p>
<p>　　[0]=></p>
<p>　　int(1)</p>
<p>　　[1]=></p>
<p>　　int(2)</p>
<p>　　[2]=></p>
<p>　　array(3) {</p>
<p>　　[0]=></p>
<p>　　string(1) "a"</p>
<p>　　[1]=></p>
<p>　　string(1) "b"</p>
<p>　　[2]=></p>
<p>　　string(1) "c"</p>
<p>　　}</p>
<p>　　}</p>
<p>　　*/</p>
<p>　　$b = 3.1;</p>
<p>　　$c = TRUE;</p>
<p>　　var_dump($b,$c);</p>
<p>　　/* 输出：</p>
<p>　　float(3.1)</p>
<p>　　bool(true)</p>
<p>　　*/</p>
<p>　　?></p>
<p>

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