php 如何将 var_dump 的结果捕获到字符串中？
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How can I capture the result of var_dump to a string?
提问by Mark Biek
I'd like to capture the output of var_dumpto a string.
我想捕获var_dump一个字符串的输出。
The PHP documentation says;
PHP 文档说；
As with anything that outputs its result directly to the browser, the output-control functionscan be used to capture the output of this function, and save it in a string (for example).
与直接将结果输出到浏览器的任何内容一样，输出控制函数可用于捕获此函数的输出，并将其保存在字符串中（例如）。
What would be an example of how that might work?
这将如何运作的一个例子是什么？
print_r()isn't a valid possibility, because it's not going to give me the information that I need.
print_r()不是一个有效的可能性，因为它不会给我我需要的信息。
采纳答案by Eran Galperin
Use output buffering:
使用输出缓冲：
<?php
ob_start();
var_dump($someVar);
$result = ob_get_clean();
?>
回答by inxilpro
Try var_export
尝试 var_export
You may want to check out var_export— while it doesn't provide the same output as var_dumpit does provide a second $returnparameter which will cause it to return its output rather than print it:
您可能想要查看var_export- 虽然它提供的输出与var_dump提供的第二个$return参数不同，但它会导致它返回其输出而不是打印它：
$debug = var_export($my_var, true);
Why?
为什么？
I prefer this one-liner to using ob_startand ob_get_clean(). I also find that the output is a little easier to read, since it's just PHP code.
我更喜欢这种单线使用ob_start和ob_get_clean()。我还发现输出更容易阅读，因为它只是 PHP 代码。
The difference between var_dumpand var_exportis that var_exportreturns a "parsable string representation of a variable"while var_dumpsimply dumps information about a variable. What this means in practice is that var_exportgives you valid PHP code (but may not give you quite as much information about the variable, especially if you're working with resources).
之间的差var_dump和var_export是var_export返回一个“可变的可解析的字符串表示”而var_dump简单地转储一个变量的信息。这在实践中意味着var_export为您提供有效的 PHP 代码（但可能不会为您提供有关变量的那么多信息，尤其是在您使用资源时）。
Demo:
演示：
$demo = array(
"bool" => false,
"int" => 1,
"float" => 3.14,
"string" => "hello world",
"array" => array(),
"object" => new stdClass(),
"resource" => tmpfile(),
"null" => null,
);
// var_export -- nice, one-liner
$debug_export = var_export($demo, true);
// var_dump
ob_start();
var_dump($demo);
$debug_dump = ob_get_clean();
// print_r -- included for completeness, though not recommended
$debug_printr = print_r($demo, true);
The difference in output:
输出差异：
var_export ($debug_exportin above example):
var_export（$debug_export在上面的例子中）：
array (
'bool' => false,
'int' => 1,
'float' => 3.1400000000000001,
'string' => 'hello world',
'array' =>
array (
),
'object' =>
stdClass::__set_state(array(
)),
'resource' => NULL, // Note that this resource pointer is now NULL
'null' => NULL,
)
var_dump ($debug_dumpin above example):
var_dump（$debug_dump在上面的例子中）：
array(8) {
["bool"]=>
bool(false)
["int"]=>
int(1)
["float"]=>
float(3.14)
["string"]=>
string(11) "hello world"
["array"]=>
array(0) {
}
["object"]=>
object(stdClass)#1 (0) {
}
["resource"]=>
resource(4) of type (stream)
["null"]=>
NULL
}
print_r ($debug_printrin above example):
print_r（$debug_printr在上面的例子中）：
Array
(
[bool] =>
[int] => 1
[float] => 3.14
[string] => hello world
[array] => Array
(
)
[object] => stdClass Object
(
)
[resource] => Resource id #4
[null] =>
)
Caveat: var_exportdoes not handle circular references
警告：var_export不处理循环引用
If you're trying to dump a variable with circular references, calling var_exportwill result in a PHP warning:
如果您尝试使用循环引用转储变量，调用var_export将导致 PHP 警告：
$circular = array();
$circular['self'] =& $circular;
var_export($circular);
Results in:
结果是：
Warning: var_export does not handle circular references in example.php on line 3
array (
'self' =>
array (
'self' => NULL,
),
)
Both var_dumpand print_r, on the other hand, will output the string *RECURSION*when encountering circular references.
两个var_dump和print_r，另一方面，将输出串*RECURSION*遇到循环引用时。
回答by Ian P
You could also do this:
你也可以这样做：
$dump = print_r($variable, true);
回答by Sergey Stolyarov
You may also try to use the serialize()function. Sometimes it is very useful for debugging purposes.
您也可以尝试使用该serialize()功能。有时它对于调试目的非常有用。
回答by hanshenrik
function return_var_dump(){
// It works like var_dump, but it returns a string instead of printing it.
$args = func_get_args(); // For <5.3.0 support ...
ob_start();
call_user_func_array('var_dump', $args);
return ob_get_clean();
}
回答by ZurabWeb
Also echo json_encode($dataobject);might be helpful
也echo json_encode($dataobject);可能有帮助
回答by Younis Bensalah
This function displays structured information about one or more expressions that includes its type and value.
此函数显示有关一个或多个表达式的结构化信息，包括其类型和值。
So, here is the realreturn version of PHP's var_dump(), which actually accepts a variable-length argument list:
所以，这是PHP 的真正返回版本var_dump()，它实际上接受一个可变长度的参数列表：
function var_dump_str()
{
$argc = func_num_args();
$argv = func_get_args();
if ($argc > 0) {
ob_start();
call_user_func_array('var_dump', $argv);
$result = ob_get_contents();
ob_end_clean();
return $result;
}
return '';
}
回答by Khandad Niazi
Here is the complete solution as a function:
这是作为函数的完整解决方案：
function varDumpToString ($var)
{
ob_start();
var_dump($var);
return ob_get_clean();
}
回答by selfawaresoup
If you want to have a look at a variable's contents during runtime, consider using a real debugger like XDebug. That way you don't need to mess up your source code, and you can use a debugger even while normal users visit your application. They won't notice.
如果您想在运行时查看变量的内容，请考虑使用像 XDebug 这样的真正调试器。这样你就不需要弄乱你的源代码，即使普通用户访问你的应用程序，你也可以使用调试器。他们不会注意到。
回答by Charlie Vieillard
This maybe a bit off topic.
这可能有点跑题了。
I was looking for a way to write this kind of information to the Docker log of my PHP-FPM container and came up with the snippet below. I'm sure this can be used by Docker PHP-FPM users.
我一直在寻找一种将此类信息写入 PHP-FPM 容器的 Docker 日志的方法，并想出了下面的代码片段。我确信 Docker PHP-FPM 用户可以使用它。
fwrite(fopen('php://stdout', 'w'), var_export($object, true));
