var_dump，var_export&之间的区别print_r [英] Difference between var_dump,var_export & print_r

问题描述

var_dump，var_export和print_r有什么区别?

推荐答案

var_dump 用于调试目的. var_dump始终打印结果.

// 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_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，则最好使用，但否则可能会引起误解.默认情况下，print_r打印结果，但是允许通过使用可选的$return参数作为字符串返回.

print_r is 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_r by default prints the result, but allows returning as string instead by using the optional $return parameter.

Array (
    [0] =>
    [1] =>
    [2] => 42
    [3] => Array ([0] => 42)
)

var_export 打印有效的php代码.如果您计算了一些值并希望结果在另一个脚本中作为常量，则很有用.请注意，var_export无法处理参考循环/递归数组，而var_dump和print_r会检查它们.默认情况下，var_export打印结果，但是允许通过使用可选的$return参数作为字符串返回.

var_export prints valid php code. Useful if you calculated some values and want the results as a constant in another script. Note that var_export can not handle reference cycles/recursive arrays, whereas var_dump and print_r check for these. var_export by default prints the result, but allows returning as string instead by using the optional $return parameter.

array (
  0 => '',
  1 => false,
  2 => 42,
  3 => array (0 => '42',),
)

我个人认为var_export是简洁和精确的最佳折衷.

Personally, I think var_export is the best compromise of concise and precise.

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