php var_dump,var_export & print_r 的区别
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Difference between var_dump,var_export & print_r
提问by Manish Trivedi
What is the difference between var_dump, var_exportand print_r?
之间有什么区别var_dump，var_export和print_r？
回答by phihag
var_dumpis for debugging purposes. var_dumpalways prints the result.
var_dump用于调试目的。var_dump总是打印结果。
// var_dump(array('', false, 42, array('42')));
array(4) {
[0]=> string(0) ""
[1]=> bool(false)
[2]=> int(42)
[3]=> array(1) {[0]=>string(2) "42")}
}
print_ris for debugging purposes, too, but does not include the member's type. It's a good idea to use if you know the types of elements in your array, but can be misleading otherwise. print_rby default prints the result, but allows returning as string instead by using the optional $returnparameter.
print_r也用于调试目的，但不包括成员的类型。如果您知道数组中元素的类型，那么使用它是一个好主意，但否则可能会产生误导。print_r默认情况下打印结果，但允许使用可选$return参数作为字符串返回。
Array (
[0] =>
[1] =>
[2] => 42
[3] => Array ([0] => 42)
)
var_exportprints valid php code. Useful if you calculated some values and want the results as a constant in another script. Note that var_exportcan not handle reference cycles/recursive arrays, whereas var_dumpand print_rcheck for these. var_exportby default prints the result, but allows returning as string instead by using the optional $returnparameter.
var_export打印有效的 php 代码。如果您计算了一些值并希望结果作为另一个脚本中的常量，则很有用。请注意，var_export不能处理引用循环/递归数组，而var_dump并print_r检查这些。var_export默认情况下打印结果，但允许使用可选$return参数作为字符串返回。
array (
0 => '',
1 => false,
2 => 42,
3 => array (0 => '42',),
)
Personally, I think var_exportis the best compromise of concise and precise.
我个人认为var_export是简洁和精确的最佳折衷。
回答by Nanne
var_dumpand var_exportrelate like this (from the manual)
var_dump并var_export像这样联系（来自手册）
var_export() gets structured information about the given variable. It is similar to var_dump() with one exception: the returned representation is valid PHP code.
var_export() 获取有关给定变量的结构化信息。它类似于 var_dump() ，但有一个例外：返回的表示是有效的 PHP 代码。
They differ from print_rthat var_dumpexports more information, like the datatype and the size of the elements.
他们从不同print_r的是var_dump出口更多的信息，如数据类型和元素的大小。
