php 如何正确使用 print_r 或 var_dump？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/14743342/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How do I properly use print_r or var_dump?
提问by Michael Corvis
I use the following snippet quite often when I am debugging:
我在调试时经常使用以下代码段：
echo "<pre>" . var_dump($var) . "</pre>";
And I find I usually get a nice readable output. But sometimes I just don't. I'm particularly vexed at the moment by this example:
我发现我通常会得到一个很好的可读输出。但有时我只是不这样做。我现在对这个例子特别恼火：
<?php
$username='xxxxxx';
$password='xxxxxx';
$data_url='http://docs.tms.tribune.com/tech/tmsdatadirect/schedulesdirect/tvDataDelivery.wsdl';
$start=gmdate("Y-m-d\TH:i:s\Z",time());
$stop =gmdate("Y-m-d\TH:i:s\Z",time()+3600*24);
$client = new SoapClient($data_url, array('exceptions' => 0,
'user_agent' => "php/".$_SERVER[SCRIPT_NAME],
'login' => strtolower($username),
'password' => $password));
$data = $client->download($start,$stop);
print_r($data);
?>
I don't want to reveal my credentials of course, but I am told print_r in this case will do the same as my usual snippet when in fact neither print_r nor my snippet produce anything other than runon data with no formatting at all. How can I make it pretty?!
我当然不想透露我的凭据，但有人告诉我，在这种情况下，print_r 将与我通常的代码段执行相同的操作，而实际上，print_r 和我的代码段都不会产生除 runon 数据之外的任何内容，而根本没有格式。怎么做才能好看？！
回答by rohitarora
var_dump always show you array in formatted data but too much extra stuff
var_dump 总是以格式化数据显示数组，但有太多额外的东西
var_dump($data);
but if you want formatted data here you need to use <pre>tags
但是如果你想在这里格式化数据，你需要使用<pre>标签
echo '<pre>';
print_r($data);
echo '</pre>';
回答by Nathan
var_dump() echos output directly, so if you want to capture it to a variable to provide your own formatting must use output buffers:
var_dump() 直接回显输出，因此如果要将其捕获到变量以提供自己的格式，则必须使用输出缓冲区：
ob_start();
var_dump($var);
$s = ob_get_clean();
Once this is done the variable $s now contains the output of var_dump(), so can safely:
完成此操作后，变量 $s 现在包含 var_dump() 的输出，因此可以安全地：
echo "<pre>" . $s . "</pre>";
回答by Bhuppi
var_dump is used when you want the more detail about any variable .
当您需要有关任何变量的更多详细信息时，可以使用 var_dump。
<?php
$temp = "hello" ;
echo var_dump($temp);
?>
it output as follows string(5) "hello"means it print the data type of variable and length of string and what is the content in the variable.
它输出如下string(5) "hello"表示它打印变量的数据类型和字符串的长度以及变量中的内容。
while print_r($expression) is used for printing the data like array or any other object data type which can not directly printed by echo statement.
而 print_r($expression) 用于打印数据，如数组或任何其他无法通过 echo 语句直接打印的对象数据类型。
回答by Siki
Well, print_r() is used to print and array, but in order to display the array in a pretty way you also need html tags.
嗯，print_r() 用于打印和数组，但是为了以漂亮的方式显示数组，您还需要 html 标签。
Just do the following:
只需执行以下操作：
echo "<pre>";
print_r($data);
echo "</pre>";
